Fix failing tests in FullScreenMagnificationGestureHandlerTest

1. testSingleFingerScrollAfterMagnified_startsFling: this test fails
   because the long-press detection interferes with scroll detection
   during test. Moreover, the current fake motion events in test is
   not recognized as scroll event on watches.
2. testTwoFingerDoubleTap_StateIsIdle_shouldInActivated() and
   testTwoFingerDoubleTap_StateIsActivated_shouldInIdle(): these 2 tests
   are failing because 1) the test uses the wrong delay and 2) the
   queued motion events will immediately change the state to detecting
   state from the expected state.

Flag: EXEMPT test fix only
Bug: 353772906
Fix: 353772906
Test: plug a watch and run "atest FullScreenMagnificationGestureHandlerTest"
Change-Id: I7d1efb6400fe4261df5bb191f284cc7cf7250924