Enhance the E2E test to be runnable against remote clusters on e.g. AWS EKS (#1610)

This contains apparently enough changes to the current E2E test code to make it runnable against remote Kubernetes clusters. I was actually able to make the test passing against my AWS EKS based test clusters with these changes. You still need to trigger it manually from a local checkout of the ARC repo today. But this might be the foundation for automated E2E tests against major cloud providers.

acceptance/values.yaml

@@ -1,6 +1,13 @@
 # Set actions-runner-controller settings for testing
 logLevel: "-4"
+imagePullSecrets:
+- name:
+image:
+  actionsRunnerImagePullSecrets:
+  - name:
 githubWebhookServer:
+  imagePullSecrets:
+  - name:
   logLevel: "-4"
   enabled: true
   labels: {}