If we're going to overview we might need to unstash

Flag: com.android.wm.shell.enable_bubble_bar
Test: atest NexusLauncherTests:PersistentBubbleStashControllerTest
Test: atest NexusLauncherTests:TransientBubbleStashControllerTest
Test: manual - swipe up to overview from home & from in an app, ensure
               bubble bar is unstashed
             - switch between home / overview / in app in transient
               and persistent taskbar to make sure things work
Bug: 368364143
Change-Id: I34c22b000d1fcc75489ea6da497f14def9649a20