Set bundler_args with system tests for travis_el8

Author: Daniel Carabas

.travis.yml

@@ -56,12 +56,12 @@ jobs:
       - "bundle exec rake litmus:install_module"
       env:
         PLATFORMS: travis_el7_puppet6
-        BUNDLE_WITH: system_tests
       rvm: 2.5.7
       script: ["travis_wait 45 bundle exec rake litmus:acceptance:parallel"]
       services: docker
       stage: acceptance
-    - before_script:
+    - bundler_args: --with system_tests
+      before_script:
       - "bundle exec rake 'litmus:provision_list[travis_el8]'"
       - "bundle exec rake 'litmus:install_agent[puppet6]'"
       - "bundle exec rake litmus:install_module"