dataImportCronTemplates: Remove CentOS 7 & stream 8

Both releases are now EOL with their associated containerdisks also
deprecated ahead of removal in the near future:

kubevirt/containerdisks#154
kubevirt/containerdisks#152

Conflicts:
  assets/dataImportCronTemplates/dataImportCronTemplates.yaml
  tests/func-tests/golden_image_test.go

NOTE: The conflict is due to commits c70bb07 and 4e8265f missing in
release-1.10.

Signed-off-by: Lee Yarwood <lyarwood@redhat.com>
Co-authored-by: Felix Matouschek <fmatouschek.com>

assets/dataImportCronTemplates/dataImportCronTemplates.yaml

@@ -1,23 +1,3 @@
-- metadata:
-    annotations:
-      cdi.kubevirt.io/storage.bind.immediate.requested: "true"
-    name: centos-stream8-image-cron
-    labels:
-      instancetype.kubevirt.io/default-preference: centos.8.stream
-      instancetype.kubevirt.io/default-instancetype: u1.medium
-  spec:
-    schedule: "0 */12 * * *"
-    template:
-      spec:
-        source:
-          registry:
-            url: docker://quay.io/containerdisks/centos-stream:8
-        storage:
-          resources:
-            requests:
-              storage: 10Gi
-    garbageCollect: Outdated
-    managedDataSource: centos-stream8
 - metadata:
     annotations:
       cdi.kubevirt.io/storage.bind.immediate.requested: "true"
@@ -58,23 +38,3 @@
               storage: 5Gi
     garbageCollect: Outdated
     managedDataSource: fedora
-- metadata:
-    annotations:
-      cdi.kubevirt.io/storage.bind.immediate.requested: "true"
-    name: centos-7-image-cron
-    labels:
-      instancetype.kubevirt.io/default-preference: centos.7
-      instancetype.kubevirt.io/default-instancetype: u1.medium
-  spec:
-    schedule: "0 */12 * * *"
-    template:
-      spec:
-        source:
-          registry:
-            url: docker://quay.io/containerdisks/centos:7-2009
-        storage:
-          resources:
-            requests:
-              storage: 10Gi
-    garbageCollect: Outdated
-    managedDataSource: centos7

tests/func-tests/golden_image_test.go

@@ -53,7 +53,7 @@ var (
 		Resource: "ssps",
 	}
 
-	expectedImages       = []string{"centos-7-image-cron", "centos-stream8-image-cron", "centos-stream9-image-cron", "centos8-image-cron-is", "fedora-image-cron"}
+	expectedImages       = []string{"centos-stream9-image-cron", "centos8-image-cron-is", "fedora-image-cron"}
 	imageNamespace       = defaultImageNamespace
 	expectedImageStreams = []tests.ImageStreamConfig{
 		{