Use only name in ObjectSize repr and str

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

src/frostfs_testlib/storage/dataclasses/object_size.py

@@ -7,7 +7,7 @@ class ObjectSize:
     value: int
 
     def __str__(self) -> str:
-        return f"{self.name} object size"
+        return self.name
 
     def __repr__(self) -> str:
         return self.__str__()