Make removeImeSurfaceFromWindow to one-way

We introduced IVoidResultCallback mechanism to
removeImeSurfaceFromWindow in CL[1] to simulate
two-way behavior before it become truly one-way.

InputMethodManagerService#removeImeSurfaceFromWindow()
simply post the task into its message queue hence we
should able to safely convert this method into one-way.

-. Remove IVoidResultCallback for this method
-. Rename it to removeImeSurfaceFromWindowAsync

[1]: Icb396ae5d74060af69c4ecb16723b2e37b9f2067

Bug: 179668859
Bug: 185277968
Test: Manual test with b/179668859 steps, and works fine
Test: atest CtsInputMethodTestCases
Change-Id: Id28698e263a23ec4a6e4f89438eba5d19bbbabbb