chg: change default behavior to manual

Signed-off-by: Chenhan Yu <[email protected]>

Author: ChenhanYu

.gitlab/tests.yml

@@ -1,9 +1,8 @@
 # NOTE: Make sure this file is consistent with .github/workflows/{unit,gpu}_tests.yml
 .tests-default:
   stage: tests
+  when: manual # Default manual trigger
   rules:
-    - if: $CI_PIPELINE_SOURCE == "web"
-      when: manual
     - if: $CI_PIPELINE_SOURCE != "web"
       when: never