Magnum allows to use CONTAINER_INFRA_PREFIX to specify a local
repository from which we can pull container images. This repository
defaults to the upstream one that is specified in the metrics helm
chart.

* This patch allows for the usage of CONTAINER_INFRA_PREFIX to
correctly configure the pull of the metric-server container image
from the specified repo.
* Add label metrics_server_chart_tag to allow user to specify
stable/metrics-server chart tag to use
* Add label metrics_server_enabled to allow enable/disable of
component (defaults: true)

Story: 2004816
Task: 37390

Change-Id: Idc315937a82317b76349bbe8466d900d00194953
Signed-off-by: Diogo Guerra <dy090.guerra@gmail.com>
(cherry picked from commit df52f9c9)