Convert tests to JUnit5 #1380
Description
The state of CDT tests is a mishmash of JUnit3/4/5 paradigms. Now JUnit6 has just been released and I think we should avoid also having JUnit6 intermixed.
This is an umbrella bug that all the associated work can be connected to, but there is no specific release to complete this. This is a good first issue because updating tests is a good way to become familiar with the CDT code base.