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
Change-Id: I12713e59d36526f6bc7ff373c2c8e178b108ef4e