[CPS] Disable prometheus by default

This change is made to be able to deploy CPS with default values in
environments where Prometheus ServiceMonitor is not available.

Unused metrics.serviceMonitor.enabled property is also removed.

Issue-ID: CPS-778
Signed-off-by: Bruno Sakoto <bruno.sakoto@bell.ca>
Change-Id: Ica4f3b6d9d10eceb37251090bfc501155f031b81
3 files changed