Clean up hubmode_fullscreen_vertical_swipe_fix flag

Flag has been launched to the public.

Bug: 340177049
Test: atest BouncerSwipeTouchHandlerTest ShadeTouchHandlerTest GlanceableHubContainerControllerTest
      also manually verified on device
Flag: EXEMPT removing com.android.systemui.hubmode_fullscreen_vertical_swipe_fix
Change-Id: Ie21c8132bc9a202d00dc8eeb9db3706b9ffa2952