Fix android.server.wm.LocationOnScreenTests

- Wait for stable window geometry in LocationOnScreenTests before starting the next test.

Bug: 294251291
Test: atest android.server.wm.LocationOnScreenTests
(cherry picked from https://googleplex-android-review.googlesource.com/q/change:I41273826c6949b455ff2c4f6e57c725476ef0a5d)

Change-Id: I3ea492a6a09c6c8f95f3aa2d0824b9acc3922fd8
Merged-In: I41273826c6949b455ff2c4f6e57c725476ef0a5d
2 files changed