hack: add etcd revision profiling helper

[waveywaves]

Changes

Carries forward the optional profiling helper from #10329 by @thc1006. The extracted implementation commit preserves @thc1006 as its author; the follow-up commit adapts it to current main and addresses the remaining review risks.

Add hack/etcd-revision-profile, an operator helper that reports the per-key write count and current serialized size of a PipelineRun, its TaskRuns, their Pods, and related Events. Reads are pinned to the PipelineRun's etcd revision, membership is checked through owner references and UIDs, and incomplete profiles fail unless explicitly accepted.

The helper lists Events once per namespace, verifies object identity through API rechecks rather than raw-value substring matching, supports encrypted stored values without a verification bypass, and forces the etcdctl v3 API.

The companion profiling guide is in #10826. This PR implements optional deliverable 3 of #10322.

Validation:

• go test ./hack/etcd-revision-profile -count=1
• go vet ./hack/etcd-revision-profile
• golangci-lint v2.12.2 run --modules-download-mode=vendor --max-issues-per-linter=0 --max-same-issues=0 --timeout 5m --new-from-rev=origin/main

/kind feature

Submitter Checklist

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Release Notes

NONE

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.81%. Comparing base (029a632) to head (21c64d0).
⚠️ Report is 17 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10834   +/-   ##
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  Coverage   90.81%   90.81%           
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  Files         292      292           
  Lines       22196    22196           
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  Hits        20158    20158           
  Misses       2036     2036           
  Partials        2        2           

Flag	Coverage Δ
unit-tests	90.81% <ø> (ø)

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[waveywaves]

/retest

[waveywaves]

cc @vdemeester @aThorp96