Use dedicated service for grafana ingress

What does this MR do and why?

Use dedicated service for grafana ingress

Default grafana chart ingress targets nginx that introduces an inappropriate suffix.

As we can't change chart's ingress to use that new service as backend, we define it manually.

Closes #1622 (closed)

Trivial solution would have been to set:

helmrelease_spec:
  values:
    grafana:
      service:
        targetPort: 3000  # <<< to use grafana directly and bypass nginx url rewrite

But it was breaking access from rancher UI

So we define an additional service that targets grafana port

And the grafana chart ingress uses global name as service backend, we can't use it as is, that's why we also have to define the associated ingress as an extra object.