Remove androidx dependency from WM CTS

It is only used by one test that simulates an activity
won't report idle. Actually the case can be done by
starting an animation on main thread, that is simpler
and more reliable.

This reduces the size of main testing apk from
3.2MB to 2.5MB (-1500+ classes).

Bug: 112837428
Test: atest ActivityVisibilityTests# \
      testNoHistoryActivityFinishedResumedActivityNotIdle

Change-Id: I75c030d0bfcd838968ae3950627d856424b79a41
7 files changed