Fix prometheus error on ceph dashboard

Ceph dashboard config for promethues is set to ctlplane(provisioning)
network during deployment due to which dashboard couldn't reach
prometheus API.
While the haproxy config uses storage n/w for prometheus.

This patch will update the deployment to use storage n/w for
promethus dashboard config.

Resolves: rhbz#2251176
Change-Id: I65de317bede578cf6a702980687ac55871ecf97f

tripleo_ansible/roles/tripleo_cephadm/tasks/dashboard/dashboard.yaml

@@ -82,12 +82,9 @@
 - name: Configure Monitoring Stack
   become: true
   block:
-    - name: get Grafana instance(s) addresses
+    - name: Get Prometheus VIP
       set_fact:
-        grafana_server_addrs: "{{ (grafana_server_addr | default([])) | union([hostvars[item][tripleo_ceph_dashboard_net]]) }}"
-      loop: "{{ groups['ceph_mgr'] | list }}"
-      vars:
-        tripleo_ceph_dashboard_net: "{{ service_net_map['ceph_dashboard_network'] + '_ip' }}"
+        prometheus_vip: "{{ net_vip_map[service_net_map['ceph_grafana_network']] }}"
     - name: set grafana api user
       command: "{{ tripleo_cephadm_ceph_cli }} dashboard set-grafana-api-username {{ tripleo_cephadm_grafana_admin_user }}"
     - name: set grafana api password
@@ -102,11 +99,11 @@
         - tripleo_cephadm_dashboard_protocol == "https"
     - name: set alertmanager host
       command: |
-        {{ tripleo_cephadm_ceph_cli }} dashboard set-alertmanager-api-host http://{{ grafana_server_addrs | first }}:9093
+        {{ tripleo_cephadm_ceph_cli }} dashboard set-alertmanager-api-host http://{{ prometheus_vip }}:9093
     - name: set prometheus host
       command: |
         {{ tripleo_cephadm_ceph_cli }} dashboard set-prometheus-api-host \
-        http://{{ grafana_server_addrs | first }}:{{ tripleo_cephadm_prometheus_port }}
+        http://{{ prometheus_vip }}:{{ tripleo_cephadm_prometheus_port }}
     - name: config grafana api url vip
       command: |
         {{ tripleo_cephadm_ceph_cli }} dashboard set-grafana-api-url \