[ez] Fix the wrong output length on vLLM dashboard (#7154)

Silly bug, hard to track. The `output_len` column printed the wrong
value from the `input_len` column.

---------

Signed-off-by: Huy Do <huydhn@gmail.com>

Author: huydhn

torchci/lib/benchmark/llms/utils/llmUtils.ts

@@ -374,7 +374,7 @@ const toRowData = (
         ? extraInfo["random_input_len"]
         : extraInfo["input_len"];
       row["output_len"] = extraInfo["random_output_len"]
-        ? extraInfo["random_input_len"]
+        ? extraInfo["random_output_len"]
         : extraInfo["output_len"];
     }