Fixed BugreportReceiverTest failures:

- testProgress_changeJustDetailsTouchingNotification was failing because
  the notification mechanism changed and now provides a way to expand
  and collapse the actions bar, and the test was collapsing it instead
  of opening the details dialog. It was fixed by tapping the
  notification content instead of the notification title.
- Similarly, openProgressNotification() was refactored to use the
  bugreport name instead of id.
- Uses getObject() (instead of getVisibleObject()) to get the activity
  from the intent chooser.
- Removed the redundant call to back to dismiss the keyboard, which was
  causing some tests to fail due to an accessibility bug.
- Retry a few times in case the bugreport name system property assertion
  fails, since the property is set by a background thread.
- Improved how notifications are canceled.
- Created a sleep() helper.

Besides the test case improvements, it also removed a redundant call to
setCancelable() in the main code.

BUG: 30641229
BUG: 30639703

Change-Id: Icd79fada22d0b8e4be034068c3e9143ef0134eed