feat(axiom): add support for regional edge endpoints in AxiomConfig

[toppercodes]

Summary

Axiom is working on adding regional ingest endpoints.
This PR introduces a new region field in AxiomConfig to specify the Axiom regional edge domain for data ingestion, and enhances the url field with intelligent path detection.

Configuration priority: url > region > default cloud endpoint

Key features:

• region: Domain-only format (e.g., mumbai.axiom.co) - automatically builds https://{region}/v1/ingest/{dataset}
• url: Smart path handling
  • URLs with custom paths are used as-is
  • URLs without paths maintain backwards compatibility by appending /v1/datasets/{dataset}/ingest
• Fully backwards compatible with existing configurations

Vector configuration

Using regional edge:

[sinks.axiom]
type = "axiom"
token = "${AXIOM_TOKEN}"
dataset = "my-dataset"
region = "eu-central-1.aws.edge.axiom.co"
# Result: https://eu-central-1.aws.edge.axiom.co/v1/ingest/my-dataset

Using URL with custom path (super special case):

[sinks.axiom]
type = "axiom"
token = "${AXIOM_TOKEN}"
dataset = "meh"
url = "http://localhost:3400/ingest"
# Result: http://localhost:3400/ingest (used as-is)

Using URL without path (backwards compatible):

[sinks.axiom]
type = "axiom"
token = "${AXIOM_TOKEN}"
dataset = "qoo"
url = "https://api.eu.axiom.co"
# Result: https://api.eu.axiom.co/v1/datasets/qoo/ingest

Traditional configuration (unchanged):

[sinks.axiom]
type = "axiom"
token = "${AXIOM_TOKEN}"
dataset = "foo"
# Result: https://api.axiom.co/v1/datasets/foo/ingest

URL takes precedence over region:

[sinks.axiom]
type = "axiom"
token = "${AXIOM_TOKEN}"
dataset = "test"
region = "mumbai.axiom.co"
url = "http://localhost:3400/ingest"
# Result: http://localhost:3400/ingest (url wins)

How did you test this PR?

• Added comprehensive unit tests covering all scenarios:
  • ✅ Regional edge endpoint generation (domain-only format)
  • ✅ URL with custom path (used as-is)
  • ✅ URL without path (backwards compatibility with legacy path format)
  • ✅ URL takes precedence over region when both are set
  • ✅ Default cloud endpoint when neither is set
  • ✅ Support for production, staging, and dev environments
  • ✅ Trailing slash handling
• All existing tests continue to pass, confirming full backward compatibility

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

Changelog fragment added: changelog.d/axiom_regional_edges.feature.md

References

#24038

Notes

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[ronoc]

Looking good !