Support for non-public clouds for EventHub scaler.

[v-shenoy]

Added support for three new fields in the trigger metadata for the eventhub scaler. The cloud parameter can be azureChinaCloud, azureGermanCloud, azureUSGovernmentCloud, azurePublicCloud, or private (default is azurePublicCloud).

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: eventhub
  labels: {}
spec:
  scaleTargetRef:
    name: eventhub
  triggers:
  - type: azure-eventhub
    metadata:
      direction: in
      eventHubNamespace: non-public-clouds-ns
      eventHubName: python-hub
      consumerGroup: $Default
      storageConnectionFromEnv: AzureWebJobsStorage
      cloud: "private"
      endpointSuffix: <service-bus-suffix>
      activeDirectoryEndpoint: <ad-endpoint>
    authenticationRef:
      name: eventhub-trigger-auth
---

Checklist

• Commits are signed with Developer Certificate of Origin (DCO - learn more)
• Tests have been added
• A PR is opened to update our Helm chart (repo) (if applicable, ie. when deployment manifests are modified)
• A PR is opened to update the documentation on (repo) (if applicable)
• Changelog has been updated and is aligned with our changelog requirements

Fixes #1915, #2781

[JorTurFer]

LGTM,
only small nits inline
Thanks for this improvement! ❤️

[zroubalik]

LGTM