There are a lot of tests that use multiple long running @run statements which prevents jtreg from parallelizing them. We should put them into separate groups to enable jtreg parallelization.

Example:
Running compiler/valhalla/inlinetypes/TestFieldNullMarkers.java without additional flags on linux-x64-debug in our CI:
- Needs ~13min
- Splitting into groups only needs ~4-5min