[Remote Store] Add minTranslogGeneration to remote translog metadata filename

[sachinpkale]

Description

• Currently, remote translog metadata file has following format:
  metadata__<inverted primary term>__<inverted tranlog generation>__<inverted creation timestamp>__nodeId__<metadata version>
• Although this works for ordering metadata files in reverse chronological order, just by looking at the metadata file name, it does not provide info on min generation referred.
• To make debugging easy, in this PR, we are adding min translog generation as part of remote translog metadata.

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

✅ Gradle check result for c578228: SUCCESS

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.79%. Comparing base (acee2ae) to head (c578228).
Report is 22 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #15489      +/-   ##
============================================
- Coverage     71.87%   71.79%   -0.08%     
+ Complexity    63318    63238      -80     
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  Files          5231     5233       +2     
  Lines        296521   296522       +1     
  Branches      42832    42827       -5     
============================================
- Hits         213113   212884     -229     
- Misses        65948    66129     +181     
- Partials      17460    17509      +49     

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