message: Fix the error message reported by Clippy
  error: this function's return value is unnecessarily wrapped by Result
  utils/src/metrics.rs:411:5
diff: @@ -408,8 +408,8 @@ impl GlobalIOStats {
  .map_err(IoStatsError::Serialize)
  }
  - fn export_latest_read_files(&self) -> Result<String, IoStatsError> {
  - Ok(serde_json::json!(self.recent_read_files.bitmap_to_array_and_clear()).to_string())
  + fn export_latest_read_files(&self) -> String {
  + serde_json::json!(self.recent_read_files.bitmap_to_array_and_clear()).to_string()
  }
  fn export_files_access_patterns(&self) -> Result<String, IoStatsError> {
  @@ -484,7 +484,7 @@ pub fn export_files_stats(
  if !latest_read_files {
  v.export_files_stats()
  } else {
  - v.export_latest_read_files()
  + Ok(v.export_latest_read_files())
  }
  })?,
  None => {
  @@ -493,7 +493,7 @@ pub fn export_files_stats(
  return if !latest_read_files {
  ios.export_files_stats()
  } else {
  - ios.export_latest_read_files()
  + Ok(ios.export_latest_read_files())
  };
  }
  }
  