[skip ci]Add comments in chaos checker (#9082)

Signed-off-by: Nyanliang567 <yanliang.qiao@zilliz.com>

tests/python_client/chaos/checker.py

@@ -80,6 +80,7 @@ class SearchChecker(Checker):
 
 
 class InsertFlushChecker(Checker):
+    """check Insert and flush operations in a dependent thread"""
     def __init__(self, flush=False):
         super().__init__()
         self._flush = flush