Revert "Adopting the DPL governance model for Mistral"

This reverts commit cfba0f3435a84608983c0c860347d301312f9a9e.

Reason for revert : For the new cycle Bobcat, there is
at least one candidacy made for Mistral PTL position.

Change-Id: I5dca14695dbf476dfea7e7e1757070389c74a1c5

reference/projects.yaml

@@ -729,7 +729,10 @@ masakari:
       repos:
         - openstack/masakari-dashboard
 mistral:
-  leadership_type: distributed
+  ptl:
+    name: Axel Vanzaghi
+    irc: avanzaghi
+    email: axel.vanzaghi@axellink.fr
   irc-channel: openstack-mistral
   service: Workflow service
   mission: >
@@ -761,28 +764,6 @@ mistral:
     mistral-extra:
       repos:
         - openstack/mistral-extra
-  liaisons:
-    release:
-      - name: Axel Vanzaghi
-        irc: avanzaghi
-        email: axel.vanzaghi@axellink.fr
-      - name: Renat Akhmerov
-        irc: rakhmerov
-        email: renat.akhmerov@gmail.com
-      - name: Adriano Petrich
-        irc: apetrich
-        email: apetrich@redhat.com
-    tact-sig:
-      - name: Adriano Petrich
-        irc: apetrich
-        email: apetrich@redhat.com
-      - name: Oleg Ovcharuk
-        irc: vgvoleg
-        email: vgvoleg@gmail.com
-    security:
-      - name: Renat Akhmerov
-        irc: rakhmerov
-        email: renat.akhmerov@gmail.com
 monasca:
   ptl:
     name: Martin Chacon Piza