CI: move the manifest_tests.sh from schutzbot/ to test/cases/

The test script should have been in the test/cases/ directory in the
first place.

Signed-off-by: Tomáš Hozza <thozza@redhat.com>

.gitlab-ci.yml

@@ -86,7 +86,7 @@ Manifests:
   extends: .terraform
   script:
     - schutzbot/deploy.sh
-    - schutzbot/manifest_tests.sh ${PARALLEL_EXEC}
+    - test/cases/manifest_tests.sh ${PARALLEL_EXEC}
   parallel:
     matrix:
       - PARALLEL_EXEC: ["1/8", "2/8", "3/8", "4/8", "5/8", "6/8", "7/8", "8/8"]