[core.http] Add warning header to deprecated endpoints

[jesuswr]

Summary

resolves #105692

This PR adds a pre response handler that sets a warning header if the requested endpoint is deprecated.

Checklist

Check the PR satisfies following conditions.

Reviewers should verify this PR satisfies this list as well.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• This was checked for breaking HTTP API changes, and any breaking changes have been approved by the breaking-change committee. The release_note:breaking label should be applied in these situations.
• Flaky Test Runner was used on any tests changed
• The PR description includes the appropriate Release Notes section, and the correct release_note:* label is applied per the guidelines

Identify risks

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Describe the risk, its severity, and mitigation for each identified risk. Invite stakeholders and evaluate how to proceed before merging.

• See some risk examples
• ...

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[jesuswr]

/ci

[jesuswr]

/ci

[elasticmachine]

💔 Build Failed

• Buildkite Build
• Commit: 3f3e276

Failed CI Steps

• x-pack/test/cases_api_integration/security_and_spaces/config_trial.ts
• x-pack/test/cases_api_integration/security_and_spaces/config_trial.ts
• FTR Configs #19
• FTR Configs #19

Test Failures

• [job] [logs] FTR Configs #19 / cases security and spaces enabled: basic Common get_all_comments deprecations should return a warning header
• [job] [logs] FTR Configs #19 / cases security and spaces enabled: basic Common get_all_comments deprecations should return a warning header
• [job] [logs] x-pack/test/cases_api_integration/security_and_spaces/config_trial.ts / cases security and spaces enabled: trial Common get_all_comments deprecations should return a warning header
• [job] [logs] x-pack/test/cases_api_integration/security_and_spaces/config_trial.ts / cases security and spaces enabled: trial Common get_all_comments deprecations should return a warning header

Metrics [docs]

✅ unchanged

History

• 💔 Build #265257 failed 374e045

cc @jesuswr