[#184] Add streaming param

Signed-off-by: Andrey Berezin <a.berezin@yadro.com>

src/frostfs_testlib/load/load_config.py

@@ -221,6 +221,8 @@ class LoadParams:
     )
     # Percentage of filling of all data disks on all nodes
     fill_percent: Optional[float] = None
+    # if set, the payload is generated on the fly and is not read into memory fully.
+    streaming: Optional[int] = metadata_field(all_load_scenarios, None, "STREAMING", False)
 
     # ------- COMMON SCENARIO PARAMS -------
     # Load time is the maximum duration for k6 to give load. Default is the BACKGROUND_LOAD_DEFAULT_TIME value.