[Drag To Hide] Fix test case fail

Root Cause: onDetachedFromWindow_menuIsGone will fail due to menuView is visible with no content under drag to hide feature enabled
Solution: Don't need to show menuView if there is no content contains

Bug: 298718415
Flag: ACONFIG com.android.systemui.floating_menu_drag_to_hide DEVELOPMENT
Test: atest MenuViewLayerTest
Change-Id: Id5abc9965fe468bd2c2c0890bd1256009dbd9473
2 files changed