[-1] Fix bug where connecting to external display prevents user from swiping out of -1.

When connecting or disconnecting device to external display, don't reparent home_task_overlay_container to external display's home task's root surface, or null. This is because -1 is only for default display.

Fix: 365936872
Test: manual
Flag: NONE - released code
Change-Id: I1e94f9d1e0fa855072010c8271f67802788d29ad