RequestExecutorBase doesn't set query timeout when passed in token is cancellable

The RequestExecutorBase has a utility function that managed cancellation tokens, where by it receives a cancelaltion token as an input argument (may be CancellationToken.None) and created a linked Token Source. However, it should always set the new token source's timeout to the query request timeout but only does it if the passed in token is not cancellable (ie a default value).

This new linked token source should always set the timeout using the request timeout.