Add tests with empty map

Signed-off-by: anikeev-yadro <a.anikeev@yadro.com>

pytest_tests/helpers/cluster.py

@@ -1,4 +1,5 @@
 import random
+import pathlib
 import re
 from dataclasses import dataclass
 from typing import Any
@@ -110,7 +111,14 @@ class InnerRingNode(NodeBase):
         since frostfs network will still treat it as "node"
     """
 
-    pass
+    def get_netmap_cleaner_threshold(self) -> str:
+        config_file = self.get_remote_config_path()
+        contents = self.host.get_shell().exec(f"cat {config_file}").stdout
+
+        config = yaml.safe_load(contents)
+        value = config["netmap_cleaner"]["threshold"]
+
+        return value
 
 
 class S3Gate(NodeBase):