Touchpad: remove tap dragging flag

This feature has now launched, so we can remove the flag.

Bug: 349562564
Test: toggle tap dragging setting, check tap dragging works when it's
      enabled but not when it's disabled
Flag: EXEMPT removing com.android.hardware.input.touchpad_tap_dragging
Change-Id: I6454b57b97f93e5cccfafc784f3fdc63a16f80ed

src/com/android/settings/inputmethod/TrackpadTapDraggingPreferenceController.java

@@ -49,9 +49,7 @@ public class TrackpadTapDraggingPreferenceController extends TogglePreferenceCon
 
     @Override
     public int getAvailabilityStatus() {
-        boolean isTouchpad = InputPeripheralsSettingsUtils.isTouchpad();
-        return (InputSettings.isTouchpadTapDraggingFeatureFlagEnabled() && isTouchpad)
-                ? AVAILABLE : CONDITIONALLY_UNAVAILABLE;
+        return InputPeripheralsSettingsUtils.isTouchpad() ? AVAILABLE : CONDITIONALLY_UNAVAILABLE;
     }
 
     @Override