ln: don't show error when overwriting a link with -sfn (#7449)

* ln: fix #6350

* test(ln): test_symlink_no_deref_dir success has no stderr

src/uu/ln/src/ln.rs

@@ -301,6 +301,7 @@ fn link_files_in_dir(files: &[PathBuf], target_dir: &Path, settings: &Settings)
                     show_error!("Could not update {}: {e}", target_dir.quote());
                 };
             }
+            #[cfg(windows)]
             if target_dir.is_dir() {
                 // Not sure why but on Windows, the symlink can be
                 // considered as a dir

tests/by-util/test_ln.rs

@@ -549,7 +549,11 @@ fn test_symlink_no_deref_dir() {
     scene.ucmd().args(&["-sn", dir1, link]).fails();
 
     // Try with the no-deref
-    scene.ucmd().args(&["-sfn", dir1, link]).succeeds();
+    scene
+        .ucmd()
+        .args(&["-sfn", dir1, link])
+        .succeeds()
+        .no_stderr();
     assert!(at.dir_exists(dir1));
     assert!(at.dir_exists(dir2));
     assert!(at.is_symlink(link));