This change replaces charmed MongoDB with Bitnami helm chart. The
values passed to the helm chart use the same service name that existed
previously, mongodb-k8s, so that no other changes are required in the
rest of modules.
It also modifies OSM health checks to successfully pass mongodb health
check.
Change-Id: I52b938598314ed75d2f248e9399dcae60934bd3e
Signed-off-by: zamre <rzamre@indracompany.com>