jicofo,prosody: migrate to new reservations system

It's now implemented in Prosody rather than in Jicofo.

jicofo/rootfs/defaults/jicofo.conf

@@ -156,11 +156,4 @@ jicofo {
       trusted-domains = [ "{{ $XMPP_RECORDER_DOMAIN }}" ]
       {{ end }}
     }
-
-    {{ if .Env.JICOFO_RESERVATION_ENABLED | default "false" | toBool }}
-    reservation {
-      enabled = "{{ .Env.JICOFO_RESERVATION_ENABLED }}"
-      base-url = "{{ .Env.JICOFO_RESERVATION_REST_BASE_URL }}"
-    }
-    {{ end }}
 }