Remove unnecessary subfolder wrappers for integration tests

[lihaoyi]

Since #3347 made all test suites run with pwd in the test's .dest folder by default, we are already guaranteed that different concurrent test suites will not collide, so we do not need the out/blah/blah segments to avoid conflicts

[lefou]

Does that mean, we can't no longer inspect the out files of multiple (failed) tests?

[lihaoyi]

Yes. But previously they were all in out/<random-number> folders, so trying to find the output of a particular test was impossible anyway from my experience. We can definitely try to add more logic to assign each test a unique folder

[lefou]

I never experienced those random number paths, this was probably after your test suite refactoring. I thought, we still had long sub-paths resembling the full test name.

[lihaoyi]

yeah the test suite refactor moved a bunch of hardcoded paths to os.temp. Made the code a lot cleaner, but at a cost of filesystem tidyness. Can probably add them back depending on sourcecode.FullName and utest.framework.TestPath to get the tidyness without the boilerplate

[lefou]

That sounds reasonable. Both generic sources (FullName as well as TestPath) already provide meaningful names. Paired with a random number, there should only one or a low count of test output directories to inspect, when in need. In LambdaTest, my Java library to write functional tests on top of JUnit/TestNG, I have a autoclosable test path provider, that can clean up automatically on success, but keeps the temp content when failed.