test: use DISTRO_CODE to select tests case

Using DISTRO_CODE simplifies test case selection and allows to test
different distro than the one test is running on.
This is used to run tests for RHEL 9.0 on F33 or RHEL 8.4

test/cases/api.sh

@@ -14,6 +14,11 @@
 
 set -euxo pipefail
 
+#TODO: remove this once there is rhel9 support for necessary image types
+if [[ $DISTRO_CODE == rhel_90 ]]; then
+    echo "Skipped"
+    exit 0
+fi
 
 #
 # Provision the software under tet.