Disable cinder services on neutron grenade jobs

We don't need it to test cinder in our jobs.
This patch disables Cinder in grenade jobs. If that will be ok
we can do the same for scenario jobs also.

This patch also enables br-ex-tcpdump and br-int-flows
services in the grenade jobs as it was missing there and
may be useful during debugging some failures of those jobs
in the future.

Conflicts:
    zuul.d/grenade.yaml

Change-Id: If490da1f7e695564a65cabf95f25c72f7639ae19
(cherry picked from commit ca3f2813c2)

zuul.d/grenade.yaml

@@ -18,12 +18,26 @@
       - ^migration/.*$
     vars:
       devstack_services:
-        c-bak: false
         etcd: false
+        br-ex-tcpdump: true
+        br-int-flows: true
+        # Cinder services
+        c-api: false
+        c-bak: false
+        c-sch: false
+        c-vol: false
+        cinder: false
+        # Swift services
         s-account: false
         s-container: false
         s-object: false
         s-proxy: false
+    group-vars:
+      subnode:
+        devstack_services:
+          # Cinder services
+          c-bak: false
+          c-vol: false
 
 - job:
     name: neutron-grenade-dvr-multinode
@@ -37,8 +51,16 @@
     irrelevant-files: *irrelevant-files
     vars:
       devstack_services:
-        c-bak: false
         etcd: false
+        br-ex-tcpdump: true
+        br-int-flows: true
+        # Cinder services
+        c-api: false
+        c-bak: false
+        c-sch: false
+        c-vol: false
+        cinder: false
+        # Swift services
         s-account: false
         s-container: false
         s-object: false
@@ -76,6 +98,9 @@
           q-agt: true
           q-l3: true
           q-meta: true
+          # Cinder services
+          c-bak: false
+          c-vol: false
         devstack_local_conf:
           post-config:
             $NEUTRON_CONF: