fix: change variable behaviour

Signed-off-by: Cédric OLIVIER <cedric3.olivier@orange.com>

templates/gitlab-ci-openshift.yml

@@ -559,7 +559,7 @@ stages:
     fi
   }
 
-  if [[ -z "$TEMPLATE_CHECK_UPDATE_DISABLED" ]]; then check_for_update openshift "1.2.1"; fi
+  if [[ "$TEMPLATE_CHECK_UPDATE_DISABLED" != "true" ]]; then check_for_update openshift "1.2.1"; fi
 
   # export tool functions (might be used in after_script)
   export -f log_info log_warn log_error assert_defined last_rollout_status force_rollout poll_last_rollout extract_oldest_tags_from_image_stream_definition purge_old_image_tags