Rewrite the broadcast receiver for ACTION_CANCEL_ENABLE_ROLLBACK (1/n)

It makes sense to remove a rollback when
ACTION_CANCEL_ENABLE_ROLLBACK is received no matter it is a new rollback
or not. For the sake of defensive programming, we don't want to remove a
rollback which is already made available or committed.

Bug: 149069841
Test: atest RollbackTest
Change-Id: I3d8004916e9438bc03fcb0c71a83617411be7379