Add a few more unittests for rstudio-workbench

[jforest]

@zachhannum @nathanchilton I am including you both here as you were tapped by Maria and Jason respectively to be helping out with the helm chart unittesting/install testing work.

[GCRev]

LGTM. I'm assuming that the Legacy Port values are not configurable and that they're always going to 9108.

[jforest]

LGTM. I'm assuming that the Legacy Port values are not configurable and that they're always going to 9108.

Exactly!

helm/charts/rstudio-workbench/templates/svc.yaml

Lines 31 to 38 in 23dbd10

	{{- if .Values.prometheus.enabled }}
	- name: metrics
	targetPort: metrics
	{{- if .Values.prometheus.legacy }}
	port: 9108
	{{- else }}
	port: {{ .Values.prometheus.port }}
	{{- end }}