revert useless change

Samples/UIWidgetsSamples_2019_4/.idea/.idea.UIWidgetsSamples_2019_4/.idea/indexLayout.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ContentModelUserStore">
-    <attachedFolders>
-      <Path>../../com.unity.uiwidgets</Path>
-    </attachedFolders>
+    <attachedFolders />
     <explicitIncludes>
       <Path>Library/PackageCache/com.unity.collab-proxy@1.2.16</Path>
       <Path>Library/PackageCache/com.unity.ext.nunit@1.0.0</Path>