Attempt to reduce flakiness of ActivityThreadTest

Make sure:
 - The test activity can be resumed. Such as any unexpected event
   unrelated to the test causes the device to sleep.
 - Test virtual displays are closed after test.

Bug: 169550676
Test: ActivityThreadTest
Change-Id: Icf6571deba11b58cbf309989c9525f245f4ea0b6
1 file changed