Port frontend fixtures specs to new nav

What does this MR do and why?

Port frontend fixtures specs to new nav

This also updates/skips affected frontend specs. Some of them are implemented in the new navigation already (To-Do count updates), and others aren't (issue count updates).

Other specs only apply to the old navigation, so are skipped for now and marked for later removal.

Part of #420121 (closed).

Screenshots or screen recordings

n/a

How to set up and validate locally

1. Does the pipeline pass?

MR acceptance checklist

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