Incorrect test count with JUnit5 parallel execution

This is reproducible in 3.0.0-M4 and in master

When running the tests in parallel, the counts don't match with the ones defined in the test.

It was raised against [JUnit|https://github.com/junit-team/junit5/issues/1975], however the team pointed out to Surefire.

The test project is [here|https://github.com/priyankshah217/junit5sample].

`mvn test`

Should give 3 for each of SampleTest and SampleTest2, but it gives 6 for SampleTest and 0 for SampleTest2