ci(k3d): guard k3d trigger jobs against recursion on stable branches

What does this MR do?

Backport !5113 (merged) to 10-0-stable to fix recursion errors seen in #6552 (closed).

Closes [CI] Pipeline on '10-0-stable' failed for commi... (#6552 - closed)

Closes [CI] Pipeline on '10-0-stable' failed for commi... (#6551 - closed)

Related issues

Author checklist

For general guidance, please follow our Contributing guide.

Required

For anything in this list which will not be completed, please provide a reason in the MR discussion.

• Merge Request Title and Description are up to date, accurate, and descriptive.
• MR targeting the appropriate branch.
• MR has a green pipeline.
• Documentation created/updated.
• Tests added/updated, and test plan for scenarios not covered by automated tests.
• Equivalent MR/issue for omnibus-gitlab opened.

Reviewers checklist

• MR has a green pipeline on https://gitlab.com/gitlab-org/charts/gitlab.
• Consider downstream impact to the Operator, as per evaluating impact from changes to GitLab chart.