Refresh test user dir on each test run

[olanti-p]

Summary

SUMMARY: Infrastructure "Fix stale config remaining between test invocations."

Purpose of change

Fix stale config poisoning consecutive test runs #3208 (review)

Describe the solution

Re-create test user dir before running tests

Testing

Before:
Run tests, change language in options to ru, run tests again, see error.
After:
No error occurs.

[scarf005]

mmm it doesn't seem to work on my end

[olanti-p]

In 1st screenshot, the config at the top of the terminal is standard user config at ./config/, not test config at ./test_user_dir/config, it's ignored when running tests.

In 2nd screenshot, you're checking contents of ./build/tests/test_user_dir, but it's the wrong folder, the tests use ./test_user_dir in current working directory, which was the top project directory, so it should be just lsd ./test_user_dir.

But digging into it further, and it's apparently failing to remove the test user dir because remove_directory is for empty directories only, so since the error is silently ignored, it proceeds with the usual broken route of using stale config. How and why did it work when I tested it I'm not sure, I must've tested wrong.

Don't code and test while sleep deprived, kids.