API: Fix default branch protection setting for Admin API

What does this MR do?

Apply correct requirements for default branch protection setting. Instead of hard-cording it, use named values.

What are the relevant issue numbers?

Closes #55111 (closed)

Does this MR meet the acceptance criteria?

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