Fix prometheus update during compute node deploy

Currently the following command fails:
`salt -C "I@prometheus" state.sls prometheus`
this is because no salt minions are matched which in turn causes the
deploy compute node pipeline to fail.

The pillar target that works is prometheus:server which targets the
correct salt minions.

PROD-Related: PROD-19010

Change-Id: Iea7633fd5a87926c3381507efba6081bbcdcd0c2
diff --git a/openstack-compute-install.groovy b/openstack-compute-install.groovy
index 7b9054a..7602dcf 100644
--- a/openstack-compute-install.groovy
+++ b/openstack-compute-install.groovy
@@ -98,9 +98,15 @@
                 }
             }
 
-        stage("Install monitoring") {
+        stage("Update/Install monitoring") {
+            //Collect Grains
+            salt.enforceState(pepperEnv, targetLiveAll, 'salt.minion.grains')
+            salt.runSaltProcessStep(pepperEnv, targetLiveAll, 'saltutil.refresh_modules')
+            salt.runSaltProcessStep(pepperEnv, targetLiveAll, 'mine.update')
+            sleep(5)
+
             salt.enforceState(pepperEnv, targetLiveAll, 'prometheus')
-            salt.enforceState(pepperEnv, 'I@prometheus', 'prometheus')
+            salt.enforceState(pepperEnv, 'I@prometheus:server', 'prometheus')
         }
 
         } catch (Throwable e) {