CI: add grafana to monasca image list

Without this patch, if there is a change to kolla in the dependency tree
then the monasca scenario does not build grafana, and therefore fails
when trying to pull it.

Change-Id: Ic0a5b9ff940c4971a74345b8812683b29c5cedbf

tests/setup_gate.sh

@@ -99,7 +99,7 @@ function prepare_images {
 
     if [[ $SCENARIO == "monasca" ]]; then
         # FIXME(mgoddard): No need for OpenStack core images.
-        GATE_IMAGES+=",^elasticsearch,^influxdb,^kafka,^kibana,^logstash,^monasca,^storm,^zookeeper"
+        GATE_IMAGES+=",^elasticsearch,^grafana,^influxdb,^kafka,^kibana,^logstash,^monasca,^storm,^zookeeper"
     fi
     sudo tee -a /etc/kolla/kolla-build.conf <<EOF
 [profiles]