Revert "Do not block autofill on waiting for the IME response"

This reverts commit 69471c8f.

Reason for revert:
Caused a deadlock between AutofillManagerService#mLock and
InlineSuggestionsRequestCallbackImpl#mLock.

Bug: 150757314
Fix: 151580124
Test: presubmit
Change-Id: Ic021facea34cbc34ad5e113790e739ab7f472c1f