chore(magnification): remove flag...

chore(magnification): remove flag delay_notification_to_magnification_when_recents_window_to_front_transition usage

The flag has been already in nextfood for 2 monthes. Remove the flag
usage then we'll delete the flag after released.

Bug: 358504284
Flag: com.android.window.flags.delay_notification_to_magnification_when_recents_window_to_front_transition
Test: manually
      atest FullScreenMagnificationControllerTest
      atest FullScreenMagnificationGestureHandlerTest
Change-Id: I4961e674109c7371e9a75a7f7189faa3d3f88ea0