enhance: [2.4] Add thread watcher to provide actual thread num (#37905)

[congqixia]

Cherry pick from master
pr: #37905

Related to #37904

---

[congqixia]

wait until 2.4.17 released
/hold

[mergify]

@congqixia E2e jenkins job failed, comment /run-cpu-e2e can trigger the job again.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.65%. Comparing base (e63a2f3) to head (528a0f8).
Report is 19 commits behind head on 2.4.

Additional details and impacted files

@@            Coverage Diff             @@
##              2.4   #37921      +/-   ##
==========================================
- Coverage   79.70%   79.65%   -0.06%     
==========================================
  Files        1069     1069              
  Lines      166979   166980       +1     
==========================================
- Hits       133092   133004      -88     
- Misses      29490    29553      +63     
- Partials     4397     4423      +26     

Files with missing lines	Coverage Δ
pkg/metrics/info_metrics.go	100.00% <ø> (ø)
pkg/metrics/metrics.go	100.00% <100.00%> (ø)

... and 35 files with indirect coverage changes

[congqixia]

/run-cpu-e2e

[mergify]

@congqixia E2e jenkins job failed, comment /run-cpu-e2e can trigger the job again.

[congqixia]

/run-cpu-e2e

[congqixia]

/unhold

[czs007]

/approve
/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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