Removed theme editor review modal (#28250)

Keeps the modified-files indicator visible as a passive toolbar pill while removing 
the inherited review modal flow.  The editor already exposes file status and revert 
controls inline, so the extra modal created an unwanted duplicate review surface.

The theme editor is intended for users who need to make small, quick changes to
their theme, not as a full developer workflow. The review modal was easy to miss
and added a lot of hidden complexity to a feature we want to keep simple for now.

Users can still see when files have been modified, and can still revert changes
from the editor surface. This only removes the separate “review all changes” modal.