TouchExplorer: clear unsent hover events on action down.

When talkback is detecting gestures, we save hover events in case we want to start touch exploring. Thses need to be cleared every new interaction.
Bug: 159651900
Test: atest touchInteractionControllerTest

Change-Id: Ia340d96205064bc953df2fbe80f87bc94885af15

services/accessibility/java/com/android/server/accessibility/gestures/TouchExplorer.java

@@ -537,6 +537,8 @@ public class TouchExplorer extends BaseEventStreamTransformation
         // touch, we figure out what to do. If were waiting
         // we resent the delayed callback and wait again.
         mSendHoverEnterAndMoveDelayed.cancel();
+        // clear any hover events that might have been queued and never sent.
+        mSendHoverEnterAndMoveDelayed.clear();
         mSendHoverExitDelayed.cancel();
         // If a touch exploration gesture is in progress send events for its end.
         if (mState.isTouchExploring()) {