feat: record the duration waiting in the proxy queue

[longjiquan]

fix: #34743

[mergify]

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

[longjiquan]

rerun ut

[czs007]

/approve
/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: czs007, longjiquan

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[codecov]

Codecov Report

Attention: Patch coverage is 94.69027% with 6 lines in your changes missing coverage. Please review.

Project coverage is 80.90%. Comparing base (d294fdd) to head (6242a1f).
Report is 16 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #34744      +/-   ##
==========================================
+ Coverage   80.84%   80.90%   +0.06%     
==========================================
  Files        1175     1185      +10     
  Lines      142066   142724     +658     
==========================================
+ Hits       114849   115472     +623     
+ Misses      22826    22825       -1     
- Partials     4391     4427      +36     

Files	Coverage Δ
internal/proxy/task.go	90.43% <100.00%> (+1.45%)	⬆️
internal/proxy/task_alias.go	95.83% <100.00%> (ø)
internal/proxy/task_database.go	98.33% <100.00%> (+2.22%)	⬆️
internal/proxy/task_delete.go	92.62% <100.00%> (+0.08%)	⬆️
internal/proxy/task_index.go	83.74% <100.00%> (+2.29%)	⬆️
internal/proxy/task_scheduler.go	95.42% <100.00%> (+0.07%)	⬆️
internal/proxy/task_search.go	76.83% <ø> (+0.31%)	⬆️
internal/proxy/task_statistic.go	85.16% <100.00%> (+1.78%)	⬆️
pkg/metrics/proxy_metrics.go	100.00% <100.00%> (ø)
internal/proxy/task_insert.go	76.78% <50.00%> (+0.56%)	⬆️
... and 2 more

... and 133 files with indirect coverage changes

[czs007]

/lgtm