Address Testing Issue

Author: FastLee

src/databricks/labs/ucx/hive_metastore/table_migration_status.py

@@ -119,7 +119,7 @@ def get_seen_tables(self, *, scope: set[Table] | None = None) -> dict[str, str]:
         tables: list = []
         table_lists = Threads.gather("list tables", tasks, self.API_LIMIT)
         # Combine tuple of lists to a list
-        for table_list in table_lists:
+        for table_list in table_lists[0]:
             tables.extend(table_list)
         for table in tables:
             if not isinstance(table, TableInfo):