Create a "tests-clustering-full" target

Convenience target to encapsulate all the clustering targets that are starting to be a bit scattered:

tests-clustering-all-stacks
tests-clustered-profileservice
tests-ha-mod_cluster
tomcat-sso-clustered-tests

Shouldn't run the clustered classloader leak tests, as those are run by a separate hudson job. The regular testsuite job should run this "tests-clustering-full" target instead of the ones listed above.

This new target should also be controllable via a system property such that instead of running tests-clustering-all-stacks it runs tests-clustering (i.e. without testing with JGroups using TCP). Or perhaps use a separate convenience target. The intent of this target is to let devs easily run the clustering tests.