refactor MagnificationModeSwitchTest

We did following change in the refactor.
  1. use the spy object instead of mock object if possble to
  reduce stubbing unexpected value.
  2. Not to use ArgumentCaptor to get TouchListener.
  3. set down time to all motion events and recyle them in #tearDown().
  4. divide some tests to assert the condition clearly.

Bug: 173159759
Test: atest MagnificationModeSwitchTest
Change-Id: I2218d983541d5b6d2ea1ee7686770ba7fd4dac26