Add dry run option to custom benchmark report script and update workflow to use it

.github/scripts/custom_benchmark_report.py

@@ -346,6 +346,11 @@ if __name__ == "__main__":
     parser = argparse.ArgumentParser(
         description="Load Criterion benchmark results from JSON files and generate an HTML table with links to reports."
     )
+    parser.add_argument(
+        "--dry-run",
+        action="store_true",
+        help="Perform a dry run without writing the HTML file.",
+    )
     parser.add_argument(
         "--criterion-dir",
         type=str,
@@ -372,6 +377,12 @@ if __name__ == "__main__":
 
     args = parser.parse_args()
 
+    if args.dry_run:
+        print(
+            "Dry run mode: No files will be written. Use --dry-run to skip writing the HTML file."
+        )
+        sys.exit(0)
+
     criterion_path = Path(args.criterion_dir)
     output_file_path = Path(args.output_file)