Allow TOUCHSCREEN event observing while TouchExploration is enabled.

Bug: 344604959
Flag: com.android.server.accessibility.always_allow_observing_touch_events
Test: atest AccessibilityEndToEndTest
Test: Verified by MotionEvent-observing service on the watch
Change-Id: I309846bfd22f0a84e4d985c4831bf5b147c11b26