Switch main/3.x to use JDK21 LTS version

[peterzhuamazon]

Description

Switch main/3.x to use JDK21 LTS version

Related Issues

#16257 (comment)

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 4a8c479: TIMEOUT

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❌ Gradle check result for 4a8c479: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❌ Gradle check result for 4a8c479: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[peterzhuamazon]

Not sure why it is still have issues on gradle check.

[github-actions]

✅ Gradle check result for 4a8c479: SUCCESS

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.38%. Comparing base (f6d6aa6) to head (4a8c479).
Report is 6 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #17515      +/-   ##
============================================
- Coverage     72.47%   72.38%   -0.10%     
  Complexity    65705    65705              
============================================
  Files          5307     5310       +3     
  Lines        304774   304834      +60     
  Branches      44193    44197       +4     
============================================
- Hits         220898   220658     -240     
- Misses        65738    66157     +419     
+ Partials      18138    18019     -119     

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