fix(datadog_logs sink): Revert renaming host -> hostname

[spencergilbert]

Fixes #17147

We introduced this change as part of leveraging semantic meanings in sinks. This appears to be correct on the surface based on DD api documentation, however it has caused clear regressions in at least one user's pipelines.

As both host and hostname can be used interchangeably, it seems we should revert this change to the original behavior and collaborate with the logs intake team to have a better understanding of the desired payload as well a more concrete contract between our products.

[netlify]

✅ Deploy Preview for vector-project ready!

Name	Link
🔨 Latest commit	397ecaa
🔍 Latest deploy log	https://app.netlify.com/sites/vector-project/deploys/644ffddeeec19d00082cc8d7
😎 Deploy Preview	https://deploy-preview-17264--vector-project.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.

[netlify]

✅ Deploy Preview for vrl-playground canceled.

Name	Link
🔨 Latest commit	397ecaa
🔍 Latest deploy log	https://app.netlify.com/sites/vrl-playground/deploys/644ffddeeec19d00082cc8dc

[datadog-vectordotdev]

Datadog Report

Branch report: spencer/revert-dd_logs-hostname
Commit report: af1032f

❌ vector: 1 Failed (1 Known Flaky), 0 New Flaky, 562 Passed, 0 Skipped, 1h 8m 9.43s Wall Time

❌ Failed Tests (1)

• sources::aws_s3::integration_tests::handles_errored_status - vector - ❄️ Known flaky - Details

  Expand for error

   Test has failed
  

[neuronull]

Should we update the upgrade guide? i.e. revert #17156

[spencergilbert]

Should we update the upgrade guide? i.e. revert #17156

Depends on when/where we're releasing it?

[github-actions]

Regression Detector Results

Run ID: 4b636fad-2ce6-4dc6-97d5-782d25aec6a6
Baseline: 7570bb3
Comparison: 397ecaa
Total vector CPUs: 7

Explanation

A regression test is an integrated performance test for vector in a repeatable rig, with varying configuration for vector. What follows is a statistical summary of a brief vector run for each configuration across SHAs given above. The goal of these tests are to determine quickly if vector performance is changed and to what degree by a pull request.

Because a target's optimization goal performance in each experiment will vary somewhat each time it is run, we can only estimate mean differences in optimization goal relative to the baseline target. We express these differences as a percentage change relative to the baseline target, denoted "Δ mean %". These estimates are made to a precision that balances accuracy and cost control. We represent this precision as a 90.00% confidence interval denoted "Δ mean % CI": there is a 90.00% chance that the true value of "Δ mean %" is in that interval.

We decide whether a change in performance is a "regression" -- a change worth investigating further -- if both of the following two criteria are true:

1. The estimated |Δ mean %| ≥ 5.00%. This criterion intends to answer the question "Does the estimated change in mean optimization goal performance have a meaningful impact on your customers?". We assume that when |Δ mean %| < 5.00%, the impact on your customers is not meaningful. We also assume that a performance change in optimization goal is worth investigating whether it is an increase or decrease, so long as the magnitude of the change is sufficiently large.

2. Zero is not in the 90.00% confidence interval "Δ mean % CI" about "Δ mean %". This statement is equivalent to saying that there is at least a 90.00% chance that the mean difference in optimization goal is not zero. This criterion intends to answer the question, "Is there a statistically significant difference in mean optimization goal performance?". It also means there is no more than a 10.00% chance this criterion reports a statistically significant difference when the true difference in mean optimization goal is zero -- a "false positive". We assume you are willing to accept a 10.00% chance of inaccurately detecting a change in performance when no true difference exists.

The table below, if present, lists those experiments that have experienced a statistically significant change in mean optimization goal performance between baseline and comparison SHAs with 90.00% confidence OR have been detected as newly erratic. Negative values of "Δ mean %" mean that baseline is faster, whereas positive values of "Δ mean %" mean that comparison is faster. Results that do not exhibit more than a ±5.00% change in their mean optimization goal are discarded. An experiment is erratic if its coefficient of variation is greater than 0.1. The abbreviated table will be omitted if no interesting change is observed.

No interesting changes in experiment optimization goals with confidence ≥ 90.00% and |Δ mean %| ≥ 5.00%.

Fine details of change detection per experiment.

experiment	goal	Δ mean %	Δ mean % CI	confidence
datadog_agent_remap_datadog_logs_acks	ingress throughput	+1.77	[+1.68, +1.87]	100.00%
syslog_regex_logs2metric_ddmetrics	ingress throughput	+0.84	[+0.56, +1.13]	99.98%
otlp_http_to_blackhole	ingress throughput	+0.61	[+0.48, +0.73]	100.00%
datadog_agent_remap_blackhole_acks	ingress throughput	+0.58	[+0.45, +0.70]	100.00%
syslog_loki	ingress throughput	+0.47	[+0.40, +0.54]	100.00%
syslog_splunk_hec_logs	ingress throughput	+0.26	[+0.19, +0.32]	100.00%
http_to_http_json	ingress throughput	+0.13	[+0.09, +0.18]	100.00%
file_to_blackhole	ingress throughput	+0.04	[-0.01, +0.09]	65.59%
http_to_http_noack	ingress throughput	+0.03	[-0.03, +0.09]	48.84%
enterprise_http_to_http	ingress throughput	+0.03	[-0.01, +0.06]	71.16%
splunk_hec_to_splunk_hec_logs_noack	ingress throughput	+0.01	[-0.04, +0.05]	13.72%
splunk_hec_to_splunk_hec_logs_acks	ingress throughput	+0.00	[-0.06, +0.06]	0.40%
fluent_elasticsearch	ingress throughput	-0.00	[-0.00, -0.00]	86.88%
splunk_hec_indexer_ack_blackhole	ingress throughput	-0.01	[-0.05, +0.03]	23.14%
syslog_humio_logs	ingress throughput	-0.08	[-0.16, +0.00]	78.21%
socket_to_socket_blackhole	ingress throughput	-0.23	[-0.28, -0.19]	100.00%
http_text_to_http_json	ingress throughput	-0.28	[-0.34, -0.21]	100.00%
syslog_log2metric_humio_metrics	ingress throughput	-0.30	[-0.41, -0.18]	99.90%
otlp_grpc_to_blackhole	ingress throughput	-0.58	[-0.69, -0.46]	100.00%
datadog_agent_remap_datadog_logs	ingress throughput	-1.01	[-1.11, -0.91]	100.00%
splunk_hec_route_s3	ingress throughput	-1.18	[-1.29, -1.06]	100.00%
datadog_agent_remap_blackhole	ingress throughput	-1.47	[-1.59, -1.36]	100.00%
syslog_log2metric_splunk_hec_metrics	ingress throughput	-1.55	[-1.63, -1.47]	100.00%
http_to_http_acks	ingress throughput	-2.00	[-3.22, -0.79]	96.56%

[patricsss]

For what it's worth we spent 4 engineers and about 12 collective hours debugging this exact issue because it's not documented anywhere that $.host will clobber $.hostname.