Explicitly remove InkWindow from WM

Remove InkWindow from WM instead of marking decorView GONE.

Bug: 300546382
Test: atest StylusHandwritingTest and also verify manually that there are no dormant windows in "adb shell dumpsys window windows" using steps in bug.

Change-Id: I3b2e7c8271dd60b189d30a226a9483fb3c5cdcd9
1 file changed