Show bubble bar when hotseat icons are visible

Fixes a flicker with bubble bar briefly attempting to stash when swiping
up on home screen.
Keeps bubble bar visible when dragging an icon on home screen.

Bug: 365561149
Flag: com.android.wm.shell.enable_bubble_bar
Test: swipe up on home screen, check that bubble bar does not stash
Test: drag a home screen icon, check that bubble bar does not stash
Change-Id: Ic8f4bf6051ed437167f369e8581a631b73e839b2