e2e: pull centos image from registry.centos.org

The BlockVolume PVC tests consume the example files that refer to
"centos:latest" without registry. This means that the images will get
pulled from Docker Hub, which has rate limits preventing CI jobs from
pulling images.

Signed-off-by: Niels de Vos <ndevos@redhat.com>
(cherry picked from commit 4fd0294eb7)

# Conflicts:
#	examples/rbd/block-pod-clone.yaml

examples/rbd/block-pod-clone.yaml

@@ -0,0 +1,17 @@
+---
+apiVersion: v1
+kind: Pod
+metadata:
+  name: pod-with-block-volume-clone
+spec:
+  containers:
+    - name: centos
+      image: registry.centos.org/centos:latest
+      command: ["/bin/sleep", "infinity"]
+      volumeDevices:
+        - name: data
+          devicePath: /dev/xvda
+  volumes:
+    - name: data
+      persistentVolumeClaim:
+        claimName: block-pvc-clone