fix(sort): explicitly clean up temp directory in TmpDirWrapper::Drop

The `TmpDirWrapper::Drop` only cleared handler state without attempting
to delete the temporary directory. Cleanup relied entirely on the inner
`TempDir::Drop`, which silently ignores errors via `let _ =
remove_dir_all()`, potentially leaking `/tmp/uutils_sortXXXX`
directories.

Now `remove_tmp_dir` is called explicitly before `TempDir::Drop` runs,
providing a safety net for cases where the silent cleanup would fail.

Closes: #11728

Author: mattsu2020

src/uu/sort/src/tmp_dir.rs

@@ -171,6 +171,15 @@ impl Drop for TmpDirWrapper {
             guard.lock = None;
             guard.path = None;
         }
+        drop(guard);
+
+        // Explicitly attempt cleanup before TempDir's Drop runs silently.
+        // TempDir::drop uses `let _ = remove_dir_all()` which silently
+        // ignores errors, potentially leaking the directory.
+        #[cfg(not(any(target_os = "redox", target_os = "wasi")))]
+        if let Some(ref temp_dir) = self.temp_dir {
+            let _ = remove_tmp_dir(temp_dir.path());
+        }
     }
 }