Remove views from StatusBarView when View is detached.

Dreams were crashing SysUI. The MediaShellView was still attached after
a dream starts so the next time Dreams came up, it would still have a
parent causing SysUI to crash

Bug: 242626584
Test: atest DreamOverlayStatusBarViewControllerTest
Change-Id: Ibf14a10139e0c4d58c95be49e00992da138d1fc7