Fix flicker caused by IME hiding twice

Avoid triggering the IME hide animation if the IME is already hidden.

Flag: EXEMPT bug fix
Bug: 377329425
Bug: 379474417
Test: manual
       - Create floating bubble and expand it
       - Show IME
       - Hide IME
       - Observe bubble is not flickering
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:cff526e4ca0c137400ef0ff10f58e4944d2bdd7f)
Merged-In: I12713e59d36526f6bc7ff373c2c8e178b108ef4e
Change-Id: I12713e59d36526f6bc7ff373c2c8e178b108ef4e