_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 "/':

wasi-testsuite/tests/rust/src/bin/symlink_create.rs

Lines 65 to 68 in 697538b

	unsafe fn create_symlink_to_root(dir_fd: wasi::Fd) {
	// Create a symlink.
	wasi::path_symlink("/", dir_fd, "symlink").expect_err("creating a symlink to an absolute path");
	}