Revert "Add API for external call audio route."

Revert "Add CTS coverage for new external audio route API."

Revert submission 16308028-external-audio

Reason for revert: Don't want to launch this in T now
Reverted Changes:
I6634c752a:Add CTS coverage for new external audio route API....
Ibd1c2880e:Add API for external call audio route.
I3e262a913:Implement new external audio route.

Change-Id: I3a3eab1151b825523499058040c14696ea2887e9