Make Lock service not final

[cwperks]

Description

This PR is a non-breaking change that is a precursor for #714

Essentially, there are plugins in the OpenSearch ecosystem that are directly instantiating the LockService class from JS SPI and I am seeking to forbid this in future versions of OpenSearch in favor of using dependency injection and only instantiating within the Job Scheduler.

Ultimately, I plan to convert the LockService to an interface.

The problem with having this class marked as final, is that I cannot replace usages like https://github.com/opensearch-project/geospatial/blob/506b38356e9ff79ce5dd3ac6871f4e871af6b2aa/src/test/java/org/opensearch/geospatial/ip2geo/common/Ip2GeoLockServiceTests.java#L35 because it requires mocking.

I would like to remove final as a modifier (only in the interim) to be able to replace existing places where the LockService is instantiated and then fully replace it with an interface.

Check List

• New functionality includes testing.
• New functionality has been documented.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 33.76%. Comparing base (707ea44) to head (34996bc).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #792   +/-   ##
=========================================
  Coverage     33.76%   33.76%           
  Complexity      143      143           
=========================================
  Files            29       29           
  Lines          1380     1380           
  Branches        132      132           
=========================================
  Hits            466      466           
  Misses          877      877           
  Partials         37       37           

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