[fix][broker] Fix Metadata Event Synchronizer producer creation retry so that the producer gets created eventually

[rdhabalia]

Motivation

Currently, Metadata Event Syncrhonizer is not using scheduled-executor because of which Synchronizer is not able to recreate the event producer in case of initial failure. This PR will replace the correct schefduler and makes sure that producer will be created after the retries.

Verifying this change

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This change is a trivial rework / code cleanup without any test coverage.

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This change is already covered by existing tests, such as (please describe tests).

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This change added tests and can be verified as follows:

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• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

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Matching PR in forked repository

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@rdhabalia Please add the following content to your PR description and select a checkbox:

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.21%. Comparing base (bbc6224) to head (af81a8b).
Report is 974 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #24081      +/-   ##
============================================
+ Coverage     73.57%   74.21%   +0.64%     
+ Complexity    32624    32060     -564     
============================================
  Files          1877     1863      -14     
  Lines        139502   144308    +4806     
  Branches      15299    16458    +1159     
============================================
+ Hits         102638   107105    +4467     
+ Misses        28908    28756     -152     
- Partials       7956     8447     +491     

Flag	Coverage Δ
inttests	26.84% <0.00%> (+2.26%)	⬆️
systests	23.21% <0.00%> (-1.12%)	⬇️
unittests	73.72% <100.00%> (+0.87%)	⬆️

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

Files with missing lines	Coverage Δ
...roker/service/PulsarMetadataEventSynchronizer.java	45.56% <100.00%> (+45.56%)	⬆️

... and 1065 files with indirect coverage changes

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