Bumps OS to 3.0.0-alpha1 and JDK 21

[Gaganjuneja]

Description

This upgrades the OpenSearch version to 3.0.0-alpha1 and JDK 21. This also removes the dependency on RCA as we are not going to have active development in RCA repo going 3.0 release forward. I have removed the integration test for now but has to be built with telemetry-otel plugin and OpenSearch directly like other plugins do.

Related Issues

Resolves #[Issue number to be closed when this PR is merged]
(#509)

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 70.01%. Comparing base (9cb092f) to head (19bb1d1).
Report is 24 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #791      +/-   ##
============================================
- Coverage     70.88%   70.01%   -0.87%     
- Complexity      421      489      +68     
============================================
  Files            49       54       +5     
  Lines          3125     3518     +393     
  Branches        194      228      +34     
============================================
+ Hits           2215     2463     +248     
- Misses          785      911     +126     
- Partials        125      144      +19     

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