[ISSUE] Refactor/fix HC release workflows

[bkenez]

Describe the issue:

Version matrix generation is tightly coupled to the release workflow, causing failures and requiring manual fixes. The PR conventions check also hangs on release PRs, blocking merges.

Actual behavior:

• Version matrix generation only runs during release workflow and is skipped if the release already exists
• Failed updates require manual regeneration using make commands and creating PRs manually
• PR conventions check hangs on auto-generated release PRs

Expected behavior:

• Version matrix generation should be decoupled from releases and triggerable via workflow dispatch
• PR conventions check should skip release-please PRs

Proposed solution:

• Has a dropdown to select Camunda versions (8.8, 8.7, 8.6, etc., or "all")
• Triggers automatically after releases
• Creates PRs with changes
• Doesn't block releases

Update PR conventions to skip release-please PRs.

[hisImminence]

Comment:

• For alwaysGreen - install chart from package, not from main line.
  • current state of main already builds a HC and pushes it to the private registry (package)