There are several surefire executions defined in the testsuites pom.xml, each can use a different arquillian group (which is just a set of container configurations). There are 4 main executions: suite-client-local, suite-client-dist, suite-client-repl, suite-manual. The unstable profile is configured to run the tests marked with Unstable category, but it's only using the arquillian group from suite-manual, so if there is a unstable client test, it fails because it can't find the arquillian container definition.

Also an unrelated fix will be included with this one - l1 test is missing it's config transformation, I guess it was lost during some conflict resolution.