fix: Remove possible panic in metrics clean up.

[liurenjie1024]

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What's changed and what's your intention?

Remove possible panic in metrics cleanup.

Close #12489

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
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[codecov]

Codecov Report

Merging #13004 (1305d4d) into main (12b3535) will increase coverage by 0.02%.
Report is 1 commits behind head on main.
The diff coverage is 64.10%.

@@            Coverage Diff             @@
##             main   #13004      +/-   ##
==========================================
+ Coverage   68.26%   68.28%   +0.02%     
==========================================
  Files        1498     1498              
  Lines      252740   252565     -175     
==========================================
- Hits       172524   172457      -67     
+ Misses      80216    80108     -108     

Flag	Coverage Δ
rust	68.28% <64.10%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/batch/src/executor/group_top_n.rs	70.15% <100.00%> (ø)
src/batch/src/executor/hash_agg.rs	98.62% <100.00%> (ø)
src/batch/src/executor/join/hash_join.rs	98.49% <100.00%> (ø)
src/common/src/estimate_size/collections/heap.rs	82.10% <100.00%> (ø)
src/batch/src/task/context.rs	20.00% <0.00%> (ø)
src/common/src/memory/mem_context.rs	83.72% <54.54%> (-7.95%)	⬇️
src/batch/src/executor/row_seq_scan.rs	20.64% <0.00%> (-0.49%)	⬇️
src/batch/src/executor/generic_exchange.rs	40.80% <0.00%> (-1.01%)	⬇️
src/batch/src/monitor/stats.rs	80.11% <79.22%> (+29.54%)	⬆️

... and 5 files with indirect coverage changes

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[wenym1]

Just introduce a label guarded metrics in #12882 that will automatically remove the label when the metrics variable is dropped. May consider porting these metrics to use the label guarded one?

[liurenjie1024]

Just introduce a label guarded metrics in #12882 that will automatically remove the label when the metrics variable is dropped. May consider porting these metrics to use the label guarded one?

Done.

[liurenjie1024]

cc @wenym1 Any other comments?

[wenym1]

I just realize that the current label guarded metrics may drop the label before it is collected, which will cause a loss of metrics. I will have a new PR to fix this first.

[wenym1]

I just realize that the current label guarded metrics may drop the label before it is collected, which will cause a loss of metrics. I will have a new PR to fix this first.

Can be fixed by #13080

[wenym1]

Support for label guarded Gauge is supported in #13080 by the way. Related code in this PR can be removed.

[liurenjie1024]

Support for label guarded Gauge is supported in #13080 by the way. Related code in this PR can be removed.

I think it's already removed in this pr.

[wenym1]

Rest LGTM!