Back button/gesture is not working with Android 14 easter egg activity.

Problem: The back button does not work as keycode ACTION_BACK is not handled.

Solution: Let the superclass activity handle keycode events if not handled by this

Change-Id: Ib130eed2c8ac699adc608adc211047e346294baa
Signed-off-by: Aditya Jadhav <aditya.jadhav@oppo.com>