Removed loading spinner and color change from Publish Review button when...

Removed loading spinner and color change from Publish Review button when fetching, still disable button though.

This ended up being more complex than I anticipated. The were a number of duplicate calls being made to the server to get the pending changes list when only 1 should have been made. In addition I have ensured the button to open the review changes dropdown can't be clicked while an update is in flight.

E.g.

1. User makes a change and that data is sent to the server
2. Immediately the "Review x changes" button in the top bar becomes disabled (but not visually so that it doesn't flicker)
3. The response from the server returns and we immediately send a request to get the list of pending changes/autosaves
4. (the button remains disabled)
5. The response with the list of changes comes back and we enable the button again (and update the number of changes in the text).

Closes #3535558