Revert "Define video-call-app config option"

Revert "Add video call role"

Revert submission 12702660-VideoChatRole

Reason for revert: Feature reverted
Reverted Changes:
I07f96521c:Add video call role
I02e985f6b:Allow default video chat app role
Iaa3890228:Define video-call-app config option

Bug: 168431157
Change-Id: I7e6ee33f31fca41fc7519b04e7f4dd649887e342