chore(e2e): disable production source maps

Author: Guillaume Chau

tests/demo/vue.config.js

@@ -3,9 +3,11 @@ module.exports = {
     apollo: {
       enableMocks: false,
       enableEngine: false,
-    }
+    },
   },
 
+  productionSourceMap: false,
+
   /* Without vue-cli-plugin-apollo 0.20.0+ */
   // chainWebpack: config => {
   //   config.module