[Backport] [2.x] Update Gradle to 8.12 (#16884)

[reta]

Backport of #16884 to 2.x

[github-actions]

✅ Gradle check result for e795867: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 13.10345% with 126 lines in your changes missing coverage. Please review.

Project coverage is 71.83%. Comparing base (afb2f94) to head (e795867).
Report is 3 commits behind head on 2.x.

Files with missing lines	Patch %	Lines
...arch/gradle/precommit/TestingConventionsTasks.java	0.00%	25 Missing ⚠️
...ensearch/gradle/precommit/ThirdPartyAuditTask.java	0.00%	20 Missing ⚠️
...rg/opensearch/gradle/vagrant/VagrantShellTask.java	0.00%	8 Missing ⚠️
...g/opensearch/gradle/test/rest/CopyRestApiTask.java	0.00%	7 Missing ⚠️
...g/opensearch/gradle/test/GradleDistroTestTask.java	0.00%	6 Missing ⚠️
...opensearch/gradle/test/rest/CopyRestTestsTask.java	0.00%	6 Missing ⚠️
...ain/groovy/org/opensearch/gradle/NoticeTask.groovy	0.00%	5 Missing ⚠️
.../org/opensearch/gradle/docker/DockerBuildTask.java	0.00%	5 Missing ⚠️
...g/opensearch/gradle/precommit/LoggerUsageTask.java	0.00%	5 Missing ⚠️
...org/opensearch/gradle/precommit/PrecommitTask.java	0.00%	4 Missing ⚠️
... and 16 more

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x   #16998      +/-   ##
============================================
+ Coverage     71.79%   71.83%   +0.03%     
- Complexity    65454    65520      +66     
============================================
  Files          5316     5316              
  Lines        305529   305574      +45     
  Branches      44509    44515       +6     
============================================
+ Hits         219359   219509     +150     
+ Misses        67902    67803      -99     
+ Partials      18268    18262       -6     

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