test: add e2e test for OpenCensus to OpenTelemetry metrics migration

[khrm]

Adds TestOTelMetrics, a consolidated e2e test for the OC→OTel metrics migration in Pipelines-as-Code (PR #2567). The test scrapes two pods:

Controller (app.kubernetes.io/name=controller):

• Asserts http_client_* metrics from knative k8s client OTel instrumentation
• Asserts go_* runtime metrics
• Checks PAC application metrics (pipelines_as_code_*) are absent/present
• Asserts old OC metric names are absent

Watcher (app.kubernetes.io/name=watcher):

• Asserts kn_workqueue_* metrics (watcher uses knative reconciler)
• Asserts go_* runtime metrics

Verified locally with PAC controller and watcher deployed to kind via ko.

Relates to #2567

📝 Description of the Change

🔗 Linked GitHub Issue

Fixes #

🧪 Testing Strategy

• Unit tests
• Integration tests
• End-to-end tests
• Manual testing
• Not Applicable

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[gemini-code-assist]

Code Review

This pull request introduces a new end-to-end test (test/metrics_otel_test.go) to verify the OpenCensus-to-OpenTelemetry metrics migration in Pipelines-as-Code by scraping the controller and watcher pods' metrics endpoints. The review feedback focuses on improving test robustness and efficiency: it recommends refactoring the metrics scraping helper to return errors instead of calling t.Fatalf (which would prematurely abort the test on transient errors during polling), reusing a single pre-initialized Kubernetes client across helper functions, and adding the necessary fmt import.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.12%. Comparing base (e1a2f48) to head (b6ca870).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2811   +/-   ##
=======================================
  Coverage   60.12%   60.12%           
=======================================
  Files         210      210           
  Lines       21151    21151           
=======================================
  Hits        12716    12716           
  Misses       7642     7642           
  Partials      793      793           

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[khrm]

//gemini help

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[khrm]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a new E2E test file test/metrics_otel_test.go to verify the OpenCensus-to-OpenTelemetry metrics migration in Pipelines-as-Code by scraping and asserting metrics from the controller and watcher pods. The feedback recommends parameterizing the waitForPACMetric helper function with a labelSelector parameter. This allows reusing the helper to poll and wait for the watcher pod's metrics, resolving potential test flakiness caused by scraping the watcher metrics only once without retries.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.

[chmouel]

plesae use testcase as per convention on this repo insteda of t.Run...