Make yarn integrity check plugin a devDependency

lib/tasks/gitlab/assets.rake

@@ -8,7 +8,6 @@ namespace :gitlab do
         yarn:check
         gettext:po_to_json
         rake:assets:precompile
-        gitlab:assets:vendor
         webpack:compile
         gitlab:assets:fix_urls
       ].each(&Gitlab::TaskHelpers.method(:invoke_and_time_task))

package.json

@@ -142,8 +142,7 @@
     "webpack-cli": "^3.3.9",
     "webpack-stats-plugin": "^0.3.0",
     "worker-loader": "^2.0.0",
-    "xterm": "^3.5.0",
-    "yarn-check-webpack-plugin": "^1.2.0"
+    "xterm": "^3.5.0"
   },
   "devDependencies": {
     "@babel/plugin-transform-modules-commonjs": "^7.5.0",
@@ -199,6 +198,7 @@
     "timezone-mock": "^1.0.8",
     "vue-jest": "^4.0.0-beta.2",
     "webpack-dev-server": "^3.8.1",
+    "yarn-check-webpack-plugin": "^1.2.0",
     "yarn-deduplicate": "^1.1.1"
   },
   "resolutions": {