Add timeout overflow break handling at leaf stage

[xiangfu0]

Summary

• introduce timeoutOverflowMode plumbing in server/broker metadata
• make LeafOperator break early only if mode=BREAK and expose a TIMEOUT_OVERFLOW_REACHED stat so intermediates keep running
• add SlowMockInstanceDataManagerFactory plus TimeoutOverflowQueryRunnerTest to cover simple select, join, and aggregation cases

query with partial results query with full results

[codecov-commenter]

Codecov Report

:x: Patch coverage is 59.49367% with 64 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 63.24%. Comparing base (a23c610) to head (ccaacce). :warning: Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...pinot/query/runtime/operator/BaseJoinOperator.java	28.57%	16 Missing and 4 partials :warning:
...requesthandler/MultiStageBrokerRequestHandler.java	0.00%	16 Missing :warning:
...che/pinot/query/runtime/operator/LeafOperator.java	71.42%	7 Missing and 5 partials :warning:
...va/org/apache/pinot/query/runtime/QueryRunner.java	80.43%	4 Missing and 5 partials :warning:
...common/response/broker/BrokerResponseNativeV2.java	72.72%	1 Missing and 2 partials :warning:
...not/query/runtime/operator/MultiStageOperator.java	71.42%	1 Missing and 1 partial :warning:
...va/org/apache/pinot/spi/utils/CommonConstants.java	0.00%	2 Missing :warning:

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #17216      +/-   ##
============================================
+ Coverage     63.18%   63.24%   +0.06%     
- Complexity     1425     1428       +3     
============================================
  Files          3123     3123              
  Lines        184813   184957     +144     
  Branches      28320    28351      +31     
============================================
+ Hits         116765   116977     +212     
+ Misses        59028    58952      -76     
- Partials       9020     9028       +8     

Flag	Coverage Δ
custom-integration1	100.00% <ø> (ø)
integration	100.00% <ø> (ø)
integration1	100.00% <ø> (ø)
integration2	0.00% <ø> (ø)
java-11	63.19% <59.49%> (+0.02%)	:arrow_up:
java-21	63.19% <59.49%> (+7.29%)	:arrow_up:
temurin	63.24% <59.49%> (+0.06%)	:arrow_up:
unittests	63.24% <59.49%> (+0.06%)	:arrow_up:
unittests1	56.01% <66.19%> (+0.07%)	:arrow_up:
unittests2	33.69% <0.00%> (-0.01%)	:arrow_down:

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