endpoint identifiers: Some code cleanup.

res_pjsip_endpoint_identifier_user.c:
* Fix copy/paste error in find_endpoint().  We were using a constant
"anonymous" string instead of the passed in endpoint_name when checking
the transport domain for an endpoint match.
* Eliminate RAII_VAR in find_endpoint().
* Remove always true check in find_transport_state_in_use().
* Remove useless CMD_STOP in find_transport_state_in_use().

res_pjsip_endpoint_identifier_anonymous.c:
* Eliminate RAII_VAR in anonymous_identify().
* Remove always true check in find_transport_state_in_use().
* Remove useless CMD_STOP in find_transport_state_in_use().

Change-Id: I86924c31db5bd225ca0c1219c761b668c6f91189