which engine to use?

• using the vintage engine to start with (no test code updates foreseen, but maybe test dependencies) (auto-brought by surefire 3.0.0-M5 / BUILD-396).
  • no need to specify the engine explicitly once surefire 3.0.0.M5 is in use.

JUnit 4 deprecation strategy

• consider managing "only" JUnit 5 from now on in BOM? (or BOM 6.3?)
  • in future BOM versions - sounds better, right now the overhead would be too huge for the modules.
  • test bom - consider extracting all the test dependencies into a separate bill of materials with a potentially more rapid update cadence (Java versions, library updates in minor releases etc) (BUILD-414)

Ensure best possible parent pom config for JUnit 5

• adjust surefire config in parent poms to suit JUnit 5 best
  • surefire by default seamlessly supports both flavors, do we need an extra action?
  • should we rather consider pimping the boms to bring JUnit 5 compatible Mockito/Hamcrest? (UPD: actually JUnit 5 tests work just fine with Mockito 1, no need for urgent action).
• make sure CE/bundles can still execute tests in isolation and w/ parallel forked exec (for old UI tests)