fix(ui): use production mode when testing

This commit in vue-cli-plugin-apollo v0.16.5 fails some tests:
Akryum/vue-cli-plugin-apollo@d91afbd

Author: haoqunjiang

packages/@vue/cli-ui/package.json

@@ -7,7 +7,7 @@
     "lint": "vue-cli-service lint",
     "apollo": "cross-env VUE_APP_CLI_UI_DEV=true VUE_APP_GRAPHQL_PORT=4000 vue-cli-service apollo:watch",
     "apollo:run": "cross-env VUE_CLI_DEBUG=true VUE_CLI_IPC=vue-cli-dev vue-cli-service apollo:run",
-    "apollo:run:test": "cross-env VUE_CLI_UI_TEST=true VUE_APP_GRAPHQL_PORT=4040 VUE_APP_CLI_UI_URL=ws://localhost:4040/graphql VUE_CLI_IPC=vue-cli-test vue-cli-service apollo:watch",
+    "apollo:run:test": "cross-env VUE_CLI_UI_TEST=true VUE_APP_GRAPHQL_PORT=4040 VUE_APP_CLI_UI_URL=ws://localhost:4040/graphql VUE_CLI_IPC=vue-cli-test vue-cli-service apollo:watch --mode production",
     "prepublishOnly": "yarn run lint --no-fix && yarn run build",
     "test:e2e:dev": "cross-env VUE_APP_CLI_UI_URL=ws://localhost:4040/graphql vue-cli-service test:e2e --mode development",
     "test:e2e:run": "vue-cli-service test:e2e --mode production --headless --url=http://localhost:4040",