fix(adapter): start pprof server when profiling is enabled

[theakshaypant]

Fixes #9007

Proposed Changes

The eventing adapter framework creates and configures a ProfilingServer but never calls ListenAndServe, so the profiling port is never bound even when runtime-profiling is set to enabled in the observability ConfigMap. Start the server conditionally based on the initial config, consistent with the adapter's static observability config model.

Pre-review Checklist

• At least 80% unit test coverage
• E2E tests for any new behavior
• Docs PR for any user-facing impact
• Spec PR for any new API feature
• Conformance test for any change to the spec

Release Note

Profiling via the observability ConfigMap (`runtime-profiling: enabled`) now works correctly for components using the eventing adapter framework. Previously the profiling server was never started and port 8008 was never bound, making pprof endpoints unreachable.

Docs

Testing
My testing might have been limited to the use-case I was trying when I first ran into the original issue.
Covered three test scenarios:

1. Nothing happens when config-observability has profiling disabled
2. Enable profiling in the cm - able to access the profiling endpoints on port 8008.
3. Enable profiling in the cm and explicitly set env on my deployment PROFILING_PORT=8090 - able to access the profiling endpoints on port 8090.

[knative-prow]

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• ✅ login: theakshaypant / name: Akshay Pant (f81324b)

[knative-prow]

Welcome @theakshaypant! It looks like this is your first PR to knative/eventing 🎉

[knative-prow]

Hi @theakshaypant. Thanks for your PR.

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[creydr]

/ok-to-test

[theakshaypant]

I went through the logs from some of the failed tests and see error messages around TLS which I would guess is more of an infra issue rather than related to the PR changes. 🤔

[creydr]

I went through the logs from some of the failed tests and see error messages around TLS which I would guess is more of an infra issue rather than related to the PR changes. 🤔

Oh yes. Seems it needs #9009

[theakshaypant]

I went through the logs from some of the failed tests and see error messages around TLS which I would guess is more of an infra issue rather than related to the PR changes. 🤔

Oh yes. Seems it needs #9009

Rebased with 9009 changes.

[creydr]

/test unit-tests

[theakshaypant]

Apologies for the noise, added pprof server shutdown on context cancellation

$ go test -race -count=1 ./pkg/adapter/v2/ -timeout 60s
ok      knative.dev/eventing/pkg/adapter/v2     2.644s