Use explicit Handler callback removal for IME surface

Use explicit Handler callback removal from handler so we dont remove all
posted methods from Handler.
There should be no behavior change.

Bug: 167948419
Bug: 167948123
Bug: 233811329

Test: atest CtsInputMethodTestCases
Change-Id: I9564f5aa2430e5438b6a3d0a25967ff10661822a