Handle the phone get booted case to show accessibility floating menu

* AccessibilityManager might not ready when the phone just got booted.

Cherry picked from commit bf0ab716

Bug: 173940864
Test: atest AccessibilityFloatingMenuControllerTest
Change-Id: I0339597cd53ca5daade427fef257bfddb3b86bd8
Merged-In: I0339597cd53ca5daade427fef257bfddb3b86bd8