Use applyAsyncUnsafe() instead of apply() to apply a transaction

As suggested, applyAsyncUnsafe() can be more efficient than apply() when
apply a transaction. This CL makes the corresponding changes to
setFrameRateCateogry and setFrameRate call

Also, I reduce the frequency of the API calls by comparing the previous
frame rate (category) with the current one. We only make an API call
when they are different.

Bug: 310966165
Test: Manual Test, atest ViewRootImplTest
Change-Id: I3f0752da8d088edff4f19725dabd75bd6d11a28f