[AD] Add poll duration metric

[ahmed-mez]

What does this PR do?

Add a new agent telemetry metric autodiscovery_poll_duration (histogram) to monitor configuration poll duration in Autodiscovery.

Motivation

Better observability

Additional Notes

The metric is shared with the Cluster Agent

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

Query the metrics endpoint of the agent and the cluster agent

# HELP autodiscovery_poll_duration Poll duration distribution by config provider (in seconds).
# TYPE autodiscovery_poll_duration histogram
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="0.005"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="0.01"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="0.025"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="0.05"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="0.1"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="0.25"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="0.5"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="1"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="2.5"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="5"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="10"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-endpoints",le="+Inf"} 3
autodiscovery_poll_duration_sum{provider="kubernetes-endpoints"} 0.0066547590000000005
autodiscovery_poll_duration_count{provider="kubernetes-endpoints"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="0.005"} 2
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="0.01"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="0.025"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="0.05"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="0.1"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="0.25"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="0.5"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="1"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="2.5"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="5"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="10"} 3
autodiscovery_poll_duration_bucket{provider="kubernetes-services",le="+Inf"} 3
autodiscovery_poll_duration_sum{provider="kubernetes-services"} 0.013881554
autodiscovery_poll_duration_count{provider="kubernetes-services"} 3

Reviewer's Checklist

• If known, an appropriate milestone has been selected; otherwise the Triage milestone is set.
• Use the major_change label if your change either has a major impact on the code base, is impacting multiple teams or is changing important well-established internals of the Agent. This label will be use during QA to make sure each team pay extra attention to the changed behavior. For any customer facing change use a releasenote.
• A release note has been added or the changelog/no-changelog label has been applied.
• Changed code has automated tests for its functionality.
• Adequate QA/testing plan information is provided if the qa/skip-qa label is not applied.
• At least one team/.. label has been applied, indicating the team(s) that should QA this change.
• If applicable, docs team has been notified or an issue has been opened on the documentation repo.
• If applicable, the need-change/operator and need-change/helm labels have been applied.
• If applicable, the config template has been updated.