Update custom MR templates for gitlab-ce

What does this MR do?

Updates custom MR templates for gitlab-ce itself.

What are the relevant issue numbers?

Part of #57676 (moved)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• [n/a] Tests added for this feature/bug
• [n/a] Tested in all supported browsers
• Conforms to the code review guidelines
• [n/a] Conforms to the merge request performance guidelines
• Conforms to the style guides
• [n/a] Conforms to the database guides
• [n/a] Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• [n/a] Security reports checked/validated by reviewer