Remove remote input after ime insets animation end

As RemoteInputController#removeRemoteInput will end up to set the
notification shade to not be IME focusable and IME layering target,

If invoking this method too early before IME hide animation finished,
it will cause IME layer can't be on top of notification shade, and
should wait until that happen to fix this IME layer issue.

Fix: 174222049
Test: manual as below steps
  1) Make and install EditTextVariations
  2) Select menu -> Direct Reply to popup remote input notification.
  3) In remote input notification, press "Direct Reply Test" to input
     text and press enter button.
  4) verify if the soft-keyboard hide animation happens on top of
     the notification.
Test: atest NotificationRemoteInputManagerTest

Change-Id: I7dbc8e656505f79b1bfb198c458d3b95a645c1cb