OpenJDK tiered tests definitions have the catch-all tier4 that runs all tests not defined in the lower tiers. hotspot:tier4 has lots of them, mostly long-running vmTestbase tests, which take many hours even on a very parallel machines.

This, unfortunately, has a chilling effect on jdk:tier4, which is seldom run by contributors, because hotspot:tier4 is in the way. But, there are plenty of fast and stable tests in jdk:tier4 that can be run in jdk:tier3. jdk_svc is the example of such tests: management features (including but not limited to JFR) are important to keep from regressions, and significant subset of them runs pretty fast.

So, it makes sense to move some jdk_svc tests to jdk:tier3 to expose it to more contributors.