trial to fix long click tests

- TouchUtils.longClickView can fail if there are many events in view side.
  In that case, down event can be delivered with delay while up event
  is delivered after 1.5 x long press interval.
  Then the event will not be recognized as long press but short event.

- fundamental solution can be to send up event after detecting long press
  but adding waitForIdleSync may solve the issue by making sure that
  there is no pending events

Bug: 6420509
Bug: 6316645
Change-Id: Ic14fcb317a1753417aaa8dab20ab4478c21f9453