Make an ending IME animation clean up old inputs for the same entry

This change fixes b/227115380 which is a fairly severe issue caused
by remote inputs remaining added to RemoteInputController because
their attempts to remove themselves on defocus/detach are all blocked
by conditions like an in-progress animation. I checked all the bugs
mentioned in the commit messages of the surrounding code, and the only
one that regressed was already broken (b/264552438).

Fixes: 227115380
Test: manual and atest
Change-Id: Iba895abdbe087d85f00ab8823580baed90117fef