[skip ci] Add coments of base file on benchmark (#9350)

Signed-off-by: Nwangting0128 <ting.wang@zilliz.com>

tests/benchmark/milvus_benchmark/runners/base.py

@@ -56,6 +56,7 @@ class BaseRunner(object):
         return self._run_as_group
     
     def init_metric(self, name, collection_info=None, index_info=None, search_info=None, run_params=None, t="metric"):
+        # The locust test calls this method to pass the corresponding metric
         self._metric.collection = collection_info
         self._metric.index = index_info
         self._metric.search = search_info