wsl2 intermittent failures

    thread 'test_df::test_df_arguments_override_themselves' (37245) panicked at tests/uutests/src/lib/util.rs:2047:35:
    called `Result::unwrap()` on an `Err` value: Custom { kind: Other, error: "wait: Timeout of '30s' reached" }
    
    thread 'test_df::test_df_compatible_sync' (37210) panicked at tests/uutests/src/lib/util.rs:2047:35:
    called `Result::unwrap()` on an `Err` value: Custom { kind: Other, error: "wait: Timeout of '30s' reached" }
    
    thread 'test_df::test_df_conflicts_overriding' (37231) panicked at tests/uutests/src/lib/util.rs:2047:35:
    called `Result::unwrap()` on an `Err` value: Custom { kind: Other, error: "wait: Timeout of '30s' reached" }
    
    thread 'test_sync::test_sync_default' (46167) panicked at tests/uutests/src/lib/util.rs:2047:35:
    called `Result::unwrap()` on an `Err` value: Custom { kind: Other, error: "wait: Timeout of '30s' reached" }

    thread 'test_sync::test_sync_fs_without_files_falls_back_to_full_sync' (46171) panicked at tests/uutests/src/lib/util.rs:2047:35:
    called `Result::unwrap()` on an `Err` value: Custom { kind: Other, error: "wait: Timeout of '30s' reached" }
    
    thread 'test_sync::test_sync_no_permission_file' (46175) panicked at tests/uutests/src/lib/util.rs:2047:35:
    called `Result::unwrap()` on an `Err` value: Custom { kind: Other, error: "wait: Timeout of '30s' reached" }

https://github.com/uutils/coreutils/actions/runs/25733997721/job/75566055256?pr=12257

Start with tests/uutests/src/lib/util.rs:2047 and the linked Actions run, then reproduce the listed test_df and test_sync cases on WSL2. Done means identifying and correcting the intermittent WSL2 timeout so those tests complete without the 30-second wait failure.