[OTAGENT-512] Add config for otel agent gateway

[songy23]

What does this PR do?

Add config for otel agent gateway. The configs are currently no-op and will be implemented in the follow-up PRs.

Motivation

Start implementing otel agent gateway in operator. This is split from #2276 since #2276 is too large and is blocked by #2247

Checklist

• PR has at least one valid label: bug, enhancement, refactoring, documentation, tooling, and/or dependencies
• PR has a milestone or the qa/skip-qa label

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 37.91%. Comparing base (24f1c33) to head (65311fd).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2314   +/-   ##
=======================================
  Coverage   37.91%   37.91%           
=======================================
  Files         258      258           
  Lines       21813    21813           
=======================================
  Hits         8271     8271           
  Misses      12908    12908           
  Partials      634      634           

Flag	Coverage Δ
unittests	37.91% <ø> (ø)

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[songy23]

e2e test failures are unrelated, they also fail in mainline: http://gitlab.ddbuild.io/DataDog/datadog-operator/-/jobs/1238451465

[songy23]

/merge

[dd-devflow-routing-codex]

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2025-11-17 19:33:35 UTC ℹ️ Start processing command /merge

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2025-11-17 19:33:41 UTC ℹ️ MergeQueue: pull request added to the queue

The expected merge time in main is approximately 0s (p90).

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2025-11-17 20:02:38 UTC ℹ️ MergeQueue: This merge request was already merged

This pull request was merged directly.