Conditionally clean up mount directories based on OpenDirectory configuration

[Copilot]

open/close previously treated mount directory lifecycle inconsistently with configuration intent. This change aligns behavior so configured open paths are preserved, while temporary paths are removed after a successful close.

• Behavioral contract

  • Preserve mount directories when OpenDirectory is configured.
  • Remove mount directories (and the empty temporary parent dir) when OpenDirectory is not configured and close succeeds.

• CLI close-path cleanup logic

  • Added configuration-aware cleanup in close(...) via a remove_mount_dirs flag derived from parsed_config.OpenDirectory is None.
  • After successful unmount+crypt close, attempt to remove:
    • the per-device mount directory
    • then its parent directory (only if empty)

• Test expectation updates

  • Updated roundtrip and regression assertions to reflect:
    • temp mount dirs disappear after successful close
    • configured OpenDirectory mount dirs remain present

remove_mount_dirs = parsed_config.OpenDirectory is None
...
sdm.unmount_device(map_name)
sdm.close_decrypted_device(map_name)
if remove_mount_dirs:
    with contextlib.suppress(OSError):
        mount_dir.rmdir()
    with contextlib.suppress(OSError):
        mount_dir.parent.rmdir()