The query builder is part of Visual Studio. Thus we can't utilize it in the standalone Report Designer. You can rest assured that we are considering the implementation of a functionality that will replace the need of a query builder.
Notice you can provide the end-users with already built data access layer in an external assembly referenced by the Standalone Designer
and thus avoid the need of writing queries by hand.
Other possible solution is to use Report Templates
containing data source components in them with predefined queries, or use any SQL based environment to test the queries before passing them to the Standalone Designer
Of course you are free to search for outer implementations of query builders that can be used.
Have you tried the new visualization options in Telerik Reporting Q2 2013? You can get them from your account.