Registry PDB: Do not select registry migrations

What does this MR do?

Registry PDB: Do not select registry migrations

Do not select registry migrations by checking for the batch.kubernetes.io/job-name label.

https://kubernetes.io/docs/reference/labels-annotations-taints/#batchkubernetesio-job-name

Changelog: fixed

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.

Closes #5812