[ISSUE #10043] Make TimerMessageReputService thread pool configurable and shutdown gracefully

[Kris20030907]

Which Issue(s) This PR Fixes

Fixes #10043

Brief Description

How Did You Test This Change?

[codecov-commenter]

Codecov Report

❌ Patch coverage is 16.66667% with 30 lines in your changes missing coverage. Please review.
✅ Project coverage is 48.85%. Comparing base (50e7ffa) to head (477d663).

Files with missing lines	Patch %	Lines
.../java/org/apache/rocketmq/common/BrokerConfig.java	25.00%	9 Missing ⚠️
...ache/rocketmq/store/config/MessageStoreConfig.java	25.00%	9 Missing ⚠️
.../store/timer/rocksdb/TimerMessageRocksDBStore.java	0.00%	9 Missing ⚠️
...on/rocksdb/TransactionalMessageRocksDBService.java	0.00%	3 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop   #10044      +/-   ##
=============================================
- Coverage      48.92%   48.85%   -0.07%     
+ Complexity     13346    13325      -21     
=============================================
  Files           1373     1373              
  Lines          99700    99735      +35     
  Branches       12887    12887              
=============================================
- Hits           48776    48728      -48     
- Misses         45003    45085      +82     
- Partials        5921     5922       +1     

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