Remove weird loading state in navigation panel

[mtias]

Whenever you go to the navigation panel this state flashes in, which is quite annoying. It'd be better to not have anything there:

[annezazu]

Noting that this experience was discussed here with a suggestion to include a spinner:

We don't really use a loading state like this anywhere else. Can you replace it with a spinner? And ideally a spinner that is delayed by perhaps .2ms so that it only appears if there's actually any loading to do.

Also noting this very related (perhaps duplicate) issue here: #48682

[mtias]

There's a couple issues — the specific loading indicator used, and then the fact that it triggers all the time as you navigate back and forth which is a much bigger problem.