Revert "Integrate MON and Prometheus"

This reverts commit c5b6206a

.

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

Change-Id: Id344572277ef7b32921922eb70bf1c37ceb12f24
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>