Use mongodb charm in k8s installer

- Update JUJU_AGENT_VERSION to 2.8.6
- Use mongodb charm and update needed osm pod specs to point at it

Change-Id: I7c03ae7de6611fcacef35716646ff08bfc1ff988
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/installers/docker/osm_pods/mon.yaml b/installers/docker/osm_pods/mon.yaml
index 988054f..490889f 100644
--- a/installers/docker/osm_pods/mon.yaml
+++ b/installers/docker/osm_pods/mon.yaml
@@ -47,7 +47,7 @@
       initContainers:
       - name: kafka-mongo-test
         image: alpine:latest
-        command: ["sh", "-c", "until (nc -zvw1 kafka 9092 && nc -zvw1 mongo 27017); do sleep 3; done; exit 0"]
+        command: ["sh", "-c", "until (nc -zvw1 kafka 9092 && nc -zvw1 mongodb-k8s 27017); do sleep 3; done; exit 0"]
       containers:
       - name: mon
         image: opensourcemano/mon:8
@@ -59,6 +59,8 @@
           value: kafka
         - name: OSMMON_MESSAGE_PORT
           value: "9092"
+        - name: OSMMON_DATABASE_URI
+          value: mongodb://mongodb-k8s:27017/?replicaSet=rs0
         envFrom:
         - secretRef:
            name: mon-secret