helm: Use .Release.Namespace as default for ServiceMonitor namespace

[superbrothers]

What this PR does / why we need it:

This PR fixes to use .Release.Namespace as default for ServiceMonitor namespace.

.Values.controller.metrics.serviceMonitor.namespace is used for the ServiceMonitor namespace. If not specified, no namespace will be set. By default .Release.Namespace is expected to be used.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• CVE Report (Scanner found CVE and adding report)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation only

Which issue/s this PR fixes

How Has This Been Tested?

Before

$ helm template ingress-nginx . --namespace=ingress-nginx --set controller.metrics.enabled=true --set controller.metrics.serviceMonitor.enabled=true | grep "kind: ServiceMonitor" -A 11
kind: ServiceMonitor
metadata:
  name: ingress-nginx-controller
  labels:
    helm.sh/chart: ingress-nginx-4.7.1
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/instance: ingress-nginx
    app.kubernetes.io/version: "1.8.1"
    app.kubernetes.io/part-of: ingress-nginx
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/component: controller
spec:

$ helm template ingress-nginx . --namespace=ingress-nginx --set controller.metrics.enabled=true --set controller.metrics.serviceMonitor.enabled=true --set controller.metrics.serviceMonitor.namespace=default | grep "kind: ServiceMonitor" -A 11
kind: ServiceMonitor
metadata:
  name: ingress-nginx-controller
  namespace: "default"
  labels:
    helm.sh/chart: ingress-nginx-4.7.1
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/instance: ingress-nginx
    app.kubernetes.io/version: "1.8.1"
    app.kubernetes.io/part-of: ingress-nginx
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/component: controller

After

$ helm template ingress-nginx . --namespace=ingress-nginx --set controller.metrics.enabled=true --set controller.metrics.serviceMonitor.enabled=true | grep "kind: ServiceMonitor" -A 11
kind: ServiceMonitor
metadata:
  name: ingress-nginx-controller
  namespace: ingress-nginx
  labels:
    helm.sh/chart: ingress-nginx-4.7.1
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/instance: ingress-nginx
    app.kubernetes.io/version: "1.8.1"
    app.kubernetes.io/part-of: ingress-nginx
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/component: controller

$ helm template ingress-nginx . --namespace=ingress-nginx --set controller.metrics.enabled=true --set controller.metrics.serviceMonitor.enabled=true --set controller.metrics.serviceMonitor.namespace=default | grep "kind: ServiceMonitor" -A 11
kind: ServiceMonitor
metadata:
  name: ingress-nginx-controller
  namespace: "default"
  labels:
    helm.sh/chart: ingress-nginx-4.7.1
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/instance: ingress-nginx
    app.kubernetes.io/version: "1.8.1"
    app.kubernetes.io/part-of: ingress-nginx
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/component: controller

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added unit and/or e2e tests to cover my changes.
• All new and existing tests passed.

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[k8s-ci-robot]

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[rikatz]

/lgtm
/approve
Thanks

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rikatz, superbrothers

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• charts/ingress-nginx/OWNERS [rikatz]

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