Refactor `editor_layout`'s `isRemoving`/`isEditinging`/`isUpdating` flags

Do we need all the flags? Or can we consolidate?

The following discussion from !164268 (merged) should be addressed:

• @arfedoro started a discussion: (+1 comment)

  question (non-blocking) ❓

  No to address in this MR but I am wondering if we need both :is-removing-policy and :is-updating-policy

  When user clicks either of those buttons, should both be disabled?

  When isDeleting is happening, save button is still enabled, looks a bit odd.

  What do you think?