Don't remove devices on onHotplug()

This CL affects TV panels and Audio Systems only.
Before HdmiCecNetwork existed: devices were removed when
HotplugDetectionAction detected a hotplug out, and TIF was informed.
Before this CL: devices were removed from the CEC network onHotplug,
but the listener to inform TIF wasn't invoked. This was causing
multiple issues.
After: on TV panels and Audio Systems, only remove devices when
HotplugDetectionAction detects a hotplug out,
just like before HdmiCecNetwork existed.

Test: atest
Bug:213417037

Change-Id: I4181b4650b70101da44fd205e4df9eb566f74496
Merged-In: I4181b4650b70101da44fd205e4df9eb566f74496