Remove syncuser warning messages in wwctl that assume its use

- #1321

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

internal/pkg/api/image/image.go

@@ -195,7 +195,7 @@ func ImageImport(cip *wwapiv1.ImageImportParameter) (imageName string, err error
 	if cip.SyncUser {
 		err = image.SyncUids(cip.Name, true)
 		if err != nil {
-			err = fmt.Errorf("error in user sync, fix error and run 'syncuser' manually: %s", err)
+			err = fmt.Errorf("syncuser error: %w", err)
 			return
 		}
 	}