Update Strimzi to Java 21

[scholzj]

Type of change

• Enhancement / new feature

Description

This PR updates Strimzi to Java 21.

It is currently a Draft to see what other changes might be needed.

Checklist

• Make sure all tests pass
• Update documentation
• Try your changes from Pod inside your Kubernetes and OpenShift cluster, not just locally
• Update CHANGELOG.md

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.83%. Comparing base (db4ccfc) to head (31d1b04).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main   #12260   +/-   ##
=========================================
  Coverage     74.82%   74.83%           
- Complexity     6628     6631    +3     
=========================================
  Files           376      376           
  Lines         25348    25348           
  Branches       3401     3401           
=========================================
+ Hits          18967    18968    +1     
- Misses         4993     4995    +2     
+ Partials       1388     1385    -3     

see 4 files with indirect coverage changes

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[scholzj]

/gha run pipeline=regression,upgrade,helm-acceptance

[github-actions]

⏳ System test verification started: link

The following 10 job(s) will be executed:

• regression-brokers-and-security-amd64 (oracle-vm-8cpu-32gb-x86-64)
• regression-operators-amd64 (oracle-vm-8cpu-32gb-x86-64)
• regression-operands-amd64 (oracle-vm-8cpu-32gb-x86-64)
• regression-brokers-and-security-arm64 (oracle-vm-8cpu-32gb-arm64)
• regression-operators-arm64 (oracle-vm-8cpu-32gb-arm64)
• regression-operands-arm64 (oracle-vm-8cpu-32gb-arm64)
• upgrade-azp_kraft_upgrade-amd64 (oracle-vm-4cpu-16gb-x86-64)
• upgrade-azp_kafka_upgrade-amd64 (oracle-vm-4cpu-16gb-x86-64)
• upgrade-azp_kraft_upgrade-arm64 (oracle-vm-4cpu-16gb-arm64)
• upgrade-azp_kafka_upgrade-arm64 (oracle-vm-4cpu-16gb-arm64)

Tests will start after successful build completion.

[github-actions]

❌ System test verification failed: link