Fix overflow in breadcrumbs list mainly on mobile

What does this MR do?

Fixes an overflow bug in breadcrumbs list mainly on mobile.

Notes for reviewers: highly recommended to use feature flag compare_repo_dropdown enabled project to test. No regression is confirmed even in the legacy one, but I do not fix the existing bug in the legacy one. See #322141 (closed) for the relevant feature flag.

Screenshots (strongly suggested)

before	after
adapted from #25301 (closed), which was taken in %11.5

Does this MR meet the acceptance criteria?

Conformity

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  • I have included a changelog entry.
• Code review guidelines
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• Separation of EE specific content

Closes #25301 (closed)