e2e: Use fully qualified image name for alpine

CRI-O 1.34+ enforces short name mode by default, which refuses
to pull images with unqualified names like 'alpine' because they
are ambiguous.

Use a full image docker.io/library/alpine

Fixes #1471

Signed-off-by: Ram Lavi <ralavi@redhat.com>

e2e/templates/cni-install.yml.j2

@@ -36,7 +36,7 @@ spec:
         effect: NoSchedule
       containers:
       - name: install-cni-plugins
-        image: alpine
+        image: docker.io/library/alpine
         command: ["/bin/sh", "/scripts/install_cni.sh"]
         resources:
           requests: