Workaround for failing test & fix scrolling in tests

- Workaround issue where instrumentation will fail to finish an activity
  causing the activity to linger longer than expected (leading to issues
  with ordering of static resources like the app widget host registration)
- Fix calculation for scrolling the screen, the previous calculation
  would result in the gesture starting at the left gesture margin due
  to rounding which can trigger a back action instead of the desired
  scroll

Bug: 142351228
Change-Id: I34bdb471030518d2b983cac2badd4d8b0e7d571b