_cleanup_test_output looks dangerous

[yamt]

_cleanup_test_output uses python glob with recursive=True to find files/directories to remove. it seems very dangerous as it follows symlinks. especially when we have a test which tries to create a symlink to "/': https://github.com/WebAssembly/wasi-testsuite/blob/697538bd29676b36e7765a1e28acdf19bbe694f3/tests/rust/src/bin/symlink_create.rs#L65-L68