fix: thread-safe for RequestAggUnionRunner

[zhanghaohit]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  close long window processing core dump under stress test #1837

• What is the current behavior? (You can also link to an open issue here)
  Currently aggregator_ is re-used for every RequestAggUnionRunner::Run, which is not thread-safe if the ClusterJob is also re-used and run in multiple threads (e.g., stored procedure/deployment request).

• What is the new behavior (if this is a feature change)?
  aggregator is dynamically created for every Run

[github-actions]

SDK Test Report

  74 files    74 suites   8m 2s ⏱️
175 tests 172 ✔️ 3 💤 0 ❌
216 runs  213 ✔️ 3 💤 0 ❌

Results for commit 0806c05.

♻️ This comment has been updated with latest results.

[github-actions]

HybridSE Linux Test Report

       67 files       235 suites   5m 50s ⏱️
19 059 tests 19 057 ✔️ 2 💤 0 ❌

Results for commit 0806c05.

[github-actions]

HybridSE Mac Test Report

       67 files       235 suites   6m 23s ⏱️
19 059 tests 19 057 ✔️ 2 💤 0 ❌

Results for commit 0806c05.

[github-actions]

Linux Test Report

       57 files       186 suites   1h 6m 11s ⏱️
  8 543 tests   8 535 ✔️ 8 💤 0 ❌
12 529 runs  12 521 ✔️ 8 💤 0 ❌

Results for commit 0806c05.

[codecov]

Codecov Report

Merging #1838 (0806c05) into main (b8ff05e) will decrease coverage by 0.01%.
The diff coverage is 95.77%.

@@             Coverage Diff              @@
##               main    #1838      +/-   ##
============================================
- Coverage     73.74%   73.73%   -0.02%     
  Complexity      347      347              
============================================
  Files           614      614              
  Lines        120314   120364      +50     
  Branches       1015     1015              
============================================
+ Hits          88731    88753      +22     
- Misses        31374    31402      +28     
  Partials        209      209              

Impacted Files	Coverage Δ
hybridse/src/vm/runner.h	92.84% <ø> (ø)
hybridse/src/vm/runner.cc	67.77% <88.88%> (-0.04%)	⬇️
src/catalog/tablet_catalog_test.cc	96.26% <98.11%> (+0.11%)	⬆️
...s/query_response_time/deploy_query_response_time.h	81.25% <0.00%> (-18.75%)	⬇️
...atistics/query_response_time/query_response_time.h	78.26% <0.00%> (-4.35%)	⬇️
.../query_response_time/deploy_query_response_time.cc	97.10% <0.00%> (-2.90%)	⬇️
src/sdk/db_sdk.cc	61.67% <0.00%> (-0.46%)	⬇️
src/client/tablet_client.cc	49.63% <0.00%> (-0.21%)	⬇️
src/tablet/tablet_impl.cc	58.96% <0.00%> (-0.18%)	⬇️
src/sdk/sql_cluster_router.cc	54.84% <0.00%> (-0.13%)	⬇️
... and 3 more

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[tobegit3hub]

LGTM