Use fully-qualified image names

Replace shortnames with FQINs; this should allow tests to
run regardless of the state of registries.conf.

And, fix one broken new test that invoked 'jq' (without dot).
This usage works in Fedora, but not in RHEL.

Signed-off-by: Ed Santiago <santiago@redhat.com>

systemtest/helpers.bash

@@ -5,6 +5,9 @@ SKOPEO_BINARY=${SKOPEO_BINARY:-$(dirname ${BASH_SOURCE})/../skopeo}
 # Default timeout for a skopeo command.
 SKOPEO_TIMEOUT=${SKOPEO_TIMEOUT:-300}
 
+# Default image to run as a local registry
+REGISTRY_FQIN=${SKOPEO_TEST_REGISTRY_FQIN:-docker.io/library/registry:2}
+
 ###############################################################################
 # BEGIN setup/teardown
 
@@ -299,7 +302,7 @@ start_registry() {
         fi
 
         if ! egrep -q "^$testuser:" $AUTHDIR/htpasswd; then
-            log_and_run $PODMAN run --rm --entrypoint htpasswd registry:2 \
+            log_and_run $PODMAN run --rm --entrypoint htpasswd $REGISTRY_FQIN \
                    -Bbn $testuser $testpassword >> $AUTHDIR/htpasswd
         fi
 
@@ -332,7 +335,7 @@ start_registry() {
         log_and_run cp $CERT $TESTDIR/client-auth/
     fi
 
-    log_and_run $PODMAN run -d --name $name "${reg_args[@]}" registry:2
+    log_and_run $PODMAN run -d --name $name "${reg_args[@]}" $REGISTRY_FQIN
 
     # Wait for registry to actually come up
     timeout=10