[#91] Failover enhancements

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

src/frostfs_testlib/load/interfaces.py

@@ -50,7 +50,7 @@ class ScenarioRunner(ABC):
         """Returns True if load is running at the moment"""
 
     @abstractmethod
-    def wait_until_finish(self):
+    def wait_until_finish(self, soft_timeout: int = 0):
         """Wait until load is finished"""
 
     @abstractmethod