Notify VDM for display removal before listeners.

This allows the displays of a virtual device to be in a
consistent state when clients receive onDisplayRemoved callback.

Test: presubmit
Test: atest VirtualDeviceManagerBasicTest#getVirtualDevice_getDisplayIds --iterations=100
Fix: 301578754
Change-Id: Ida80070c525b2aa047a848ddaa8de6e817d7f51e