feat: record the duration waiting in the proxy queue (#34744)

[longjiquan]

fix: #34743
pr: #34744

[codecov]

Codecov Report

Attention: Patch coverage is 93.80531% with 7 lines in your changes missing coverage. Please review.

Project coverage is 81.18%. Comparing base (0e22650) to head (f778b51).
Report is 2 commits behind head on 2.4.

Additional details and impacted files

@@            Coverage Diff             @@
##              2.4   #34788      +/-   ##
==========================================
+ Coverage   81.15%   81.18%   +0.03%     
==========================================
  Files         786      786              
  Lines      112871   112902      +31     
==========================================
+ Hits        91602    91665      +63     
+ Misses      16869    16829      -40     
- Partials     4400     4408       +8     

Files	Coverage Δ
internal/proxy/task.go	88.87% <100.00%> (+1.42%)	⬆️
internal/proxy/task_alias.go	95.83% <100.00%> (ø)
internal/proxy/task_database.go	96.68% <100.00%> (+2.20%)	⬆️
internal/proxy/task_delete.go	92.41% <100.00%> (+0.08%)	⬆️
internal/proxy/task_index.go	82.91% <100.00%> (+2.32%)	⬆️
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	84.66% <100.00%> (+1.76%)	⬆️
pkg/metrics/proxy_metrics.go	73.68% <0.00%> (-0.56%)	⬇️
internal/proxy/task_insert.go	76.78% <50.00%> (+0.56%)	⬆️
... and 2 more

... and 17 files with indirect coverage changes

[czs007]

/approve
/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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