Fix: Add #[expect(dead_code)] to with_reverse_pages builder method

This attribute suppresses the dead code warning for Phase 1 implementation.
The method will be used in Phase 2 when actual page reversal is implemented.

Author: GaneshPatil7517

datafusion/datasource-parquet/src/opener.rs

@@ -1150,6 +1150,7 @@ mod test {
         }
 
         /// Set reverse pages flag.
+        #[expect(dead_code)]
         fn with_reverse_pages(mut self, enable: bool) -> Self {
             self.reverse_pages = enable;
             self