Handle failure to pull an external call.

Look for two expected call fail causes which can occur if an external
call is being pulled, and the pulled ImsPhoneConnection disconnects.
These call fail causes are a signal that the call pull has failed.

We use this to trigger a callback which causes the TelephonyConnection to
swap the ImsPhoneConnection out for the ImsExternalConnection.

Bug: 29906222
Change-Id: I22e570ffd578ef5e474d6abaf5d89378bd17996c