This diff cleans up the one off styles in the thread settings media gallery modal and replaces it with styles of the redesigned modal.
Linear task: https://linear.app/comm/issue/ENG-5943/extendmodify-the-modal-props-api-to-follow-new-modal-designs and https://linear.app/comm/issue/ENG-5944/fix-up-chat-media-modal
Depends on D10323