CI/molecule: use common vars as well and simplify run (#13520)

The molecule_run.sh isn't really needed since the switch to gitlab-ci
matrix runs.

Also use the inventory variables pattern for kata-containers.

.gitlab-ci/molecule.yml

@@ -1,5 +1,5 @@
 ---
-.molecule:
+molecule:
   tags: [ffci]
   rules: # run on ci-short as well
   - if: $CI_COMMIT_BRANCH =~ /^pr-.*$/
@@ -13,7 +13,8 @@
   needs:
   - pipeline-image
   script:
-  - ./tests/scripts/molecule_run.sh
+  - cd roles/$ROLE
+  - molecule test --all -- --extra-vars @${CI_PROJECT_DIR}/tests/common_vars.yml
   after_script:
   - rm -fr molecule_logs
   - mkdir -p molecule_logs
@@ -23,11 +24,6 @@
     when: always
     paths:
     - molecule_logs/
-
-molecule:
-  extends: .molecule
-  script:
-  - ./tests/scripts/molecule_run.sh -i $ROLE
   parallel:
     matrix:
     - ROLE: