[A11y] Fix failing AccessibilityInputFilter tests

Magnification should not change the way stylus/mouse events
are dispatched, and only needs to handle those events.

Bug: b/357181972
Test: Existing tests fixed, new tests added
Flag: com.android.server.accessibility.enable_magnification_follows_mouse
Change-Id: Ibf726467ef206c4b17a4913d50dae610d87920c9