RadMenu can work with asp:ScriptManager and it is not needed to have telerik:RadScriptManager.
I understand that it will be hard to manually update 154 pages, but the proper configuration would require to have a shared ScriptManager in the master page and if/when needed to put asp:ScriptManagerProxy
in the aspx pages.
Get quickly onboarded and successful
with your Telerik and/or Kendo UI products with the Virtual Classroom free technical training, available to all active customers. Learn More.