Reverted cache changes, fixed package artifacts

.gitlab-ci.yml

@@ -11,17 +11,16 @@ cache:
               - yarn.lock
               - frontend/yarn.lock
       paths:
+          - .yarn
           - node_modules
+          - frontend/.yarn
           - frontend/node_modules
 
 before_script:
-    - >
-      if [ ! -d "node_modules" ]; then
-        yarn install
-        cd frontend
-        yarn install
-        cd ..
-      fi
+    - yarn install --cache-folder .yarn --frozen-lockfile
+    - cd frontend
+    - yarn install --cache-folder .yarn --frozen-lockfile
+    - cd ..
 
 test_backend:
     stage: test
@@ -78,4 +77,7 @@ package_server:
         - mv "$TMP/"* .
     artifacts:
         paths:
-            - .
+            - package.json
+            - server.js
+            - yarn.lock
+            - frontend/