Revert "Integrate NBI and Prometheus"

This reverts commit 38f5d5834d610e011b3608fe8cc34b927775204a.

Reason for revert: Grafana-k8s requires Juju 3.1 and we are not ready
to change Juju versions at this time

Change-Id: I90dbb6e1c2921289ecaabfa636878763f981c3e1
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
diff --git a/installers/charm/osm-nbi/metadata.yaml b/installers/charm/osm-nbi/metadata.yaml
index b7902e0..8a336c8 100644
--- a/installers/charm/osm-nbi/metadata.yaml
+++ b/installers/charm/osm-nbi/metadata.yaml
@@ -67,6 +67,9 @@
   keystone:
     interface: keystone
     limit: 1
+  prometheus:
+    interface: prometheus
+    limit: 1
   ingress:
     interface: ingress
     limit: 1