Fix Protected Tags show page

Problem

There's currently a bug with the protected tags show page as it returns a 404. This happens because we're missing a show page for the protected tags.

This was introduced in !187054 (merged) but was missed because of the quarantined spec.

Solution

Add the missing page so we can render successfully. Make the quarantine on the protected_tags spec more specific to the flaky specs to re-introduce spec coverage.

References

Screenshots or screen recordings

Before	After
Screen_Recording_2025-06-03_at_06.46.46	Screen_Recording_2025-06-03_at_06.42.14

How to set up and validate locally

• Go to repository settings
• Create protected tags matching existing tags (create the tags if you don't have any)
• Click on n matching tags link

MR acceptance checklist

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Related to #509488 (closed)