Stop pulling in machine-os-content

As part of https://github.com/openshift/enhancements/blob/master/enhancements/ocp-coreos-layering/ocp-coreos-layering.md
we have switched to a new `rhel-coreos-8`.

Really, nothing else besides the MCO should be pulling in or
referencing the OS images.  I don't understand what
cross-checking the image stream tag was ever doing at all.  The
MCO owns rolling out the right OS version, and if that isn't
correct something else went seriously wrong.

Closes: openshift#101

manifests/01-openshift-imagestream.yaml

@@ -15,9 +15,4 @@ spec:
     from:
       kind: DockerImage
       name: example.com/image-reference-placeholder:driver-toolkit
-  - name: 0.0.1-snapshot-machine-os 
-    importPolicy:
-      scheduled: true
-    from:
-      kind: DockerImage
-      name: example.com/image-reference-placeholder:driver-toolkit
+

manifests/image-references

@@ -6,7 +6,3 @@ spec:
     from:
       kind: DockerImage
       name: example.com/image-reference-placeholder:driver-toolkit
-  - name: machine-os-content
-    from:
-      kind: DockerImage
-      name: registry.svc.ci.openshift.org/openshift:machine-os-content

test/e2e

@@ -62,39 +62,6 @@ test_imagestream() {
     oc get imagestream/driver-toolkit -n openshift -o yaml > ${ARTIFACT_DIR}/driver-toolkit-imagestream.yaml
 }
 
-# Check for latest and RHCOS tags
-test_imagestream_tags() {
-    rhcos_version=$(get_node_rhcos_version)
-    echo "INFO: Node RHCOS version: ${rhcos_version}"
-
-    oc get imagestream/driver-toolkit -n openshift -o json | jq ".spec.tags[].name"
-
-    image_latest=$(oc get imagestream/driver-toolkit -n openshift -o json \
-    	               | jq -r ".spec.tags[] | select(.name == \"latest\") | .from.name")
-    echo "INFO: Image from latest tag: ${image_latest}"
-
-    echo "$image_latest" > ${ARTIFACT_DIR}/latest_image.address
-
-    image_rhcos_tag=$(oc get imagestream/driver-toolkit -n openshift -o json \
-    	                  | jq  -r ".spec.tags[] | select(.name == \"${rhcos_version}\") | .from.name")
-    echo "INFO: Image from RHCOS tag: ${image_rhcos_tag}"
-
-    if [[ ${image_latest} == "" ]]; then
-	    echo "ERROR: driver-toolkit latest tag is empty string"
-	    exit 1
-    fi
-
-    if [[ ${image_rhcos_tag} == "" ]]; then
-	    echo "ERROR: driver-toolkit RHCOS version tag is empty string"
-	    exit 1
-    fi
-
-    if [[ ${image_rhcos_tag} != ${image_latest} ]]; then
-	    echo "ERROR: driver-toolkit latest and RHCOS version tags mismatch (${image_rhos_tag} != ${image_latest})"
-	    exit 1
-    fi
-}
-
 # Gets the /etc/driver-toolkit-release.json file from driver-toolkit
 # Sends the resulting filename to stdout
 get_driver_toolkit_release_file(){
@@ -199,10 +166,6 @@ echo
 echo "## TEST: Checking imagestream/driver-toolkit ##"
 test_imagestream
 
-echo
-echo "## TEST: Checking that driver-toolkit/imagestream latest and RHCOS tag are matching and non-empty ##"
-test_imagestream_tags
-
 echo
 echo "## TEST: Checking that RHEL version in driver-toolkit matches the node ##"
 test_rhel_version