add missing jitsi auth URL conditional

roles/matrix-jitsi/templates/jicofo/sip-communicator.properties.j2

@@ -3,3 +3,7 @@ org.jitsi.jicofo.BRIDGE_MUC={{ matrix_jitsi_jvb_brewery_muc }}@{{ matrix_jitsi_x
 
 org.jitsi.jicofo.jibri.BREWERY={{ matrix_jitsi_jibri_brewery_muc }}@{{ matrix_jitsi_xmpp_internal_muc_domain }}
 org.jitsi.jicofo.jibri.PENDING_TIMEOUT=90
+
+{% if matrix_jitsi_enable_auth %}
+org.jitsi.jicofo.auth.URL=XMPP:{{ matrix_jitsi_xmpp_domain }}
+{% endif %}