How to exit entire TestSuite on failure
In each Test Case there is an options menu that allows you to set a flag for "Abort on Error". I interpret this to mean that if any test step fails in the Test Case any subsequent test steps are ski...
Forum Discussion
The WsdlTestSuite class has the methods setAbortOnError and setFailOnErrors, while I have not tried this myself you could look at calling one or both these methods (to suit your requirements) via Groovy in your test suite Setup Script. Again the WsdlProject class has the same two methods.
Not sure if these will produce the behaviour you require, but might be worth investigating.