Revert "ci: disable cli-ui lintOnSave in circleci"

This reverts commit cfc69c3.

Author: fangbinwei

packages/@vue/cli-ui/vue.config.js

@@ -1,11 +1,7 @@
 const merge = require('deepmerge')
 const path = require('path')
 
-/** @type {import('@vue/cli-service').ProjectOptions} */
 module.exports = {
-  lintOnSave: process.env.CIRCLECI
-    ? false
-    : 'default',
   pluginOptions: {
     apollo: {
       enableMocks: false,