Do not run package hunter if credentials are missing

We run package hunter as part of gitlab-org and renovate. In order to
prevent the job from running on other forks that haven't set it up, we
check for the existance of PACKAGE_HUNTER_USER.

.gitlab/ci/rules.gitlab-ci.yml

@@ -1059,6 +1059,8 @@
 
 .reports:rules:package_hunter:
   rules:
+    - if: "$PACKAGE_HUNTER_USER == null || $PACKAGE_HUNTER_USER == ''"
+      when: never
     - <<: *if-default-branch-schedule-2-hourly
     - <<: *if-merge-request
       changes: ["yarn.lock"]