fix(test): use canonicalized disk root for file_sync_probe in rename_data test
On macOS, tempfile::tempdir returns /var/folders/... while LocalDisk
resolves the root to /private/var/folders/... via dunce::canonicalize.
The file_sync_probe::enter() path check uses starts_with(), so passing
the non-canonical tempdir path caused the probe to never activate,
making wait_for_active() hang indefinitely.
Use disk.root (already canonicalized) for the probe instead.
