fix: remove unnecessary iteration limit in load_all_downstream

The loop terminates when no new schemas are discovered. Since the
total number of schemas on the server is finite, this is guaranteed
to converge — even with cross-schema cycles. No safety cap needed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: dimitri-yatsenko

src/datajoint/dependencies.py

@@ -242,10 +242,7 @@ def load_all_downstream(self) -> None:
             self.load()
             return
 
-        # Safety limit: cross-schema FK chains are typically 3-5 deep.
-        # Unlike the DAG within a schema, cross-schema references could
-        # theoretically form cycles, so we cap iterations.
-        for _ in range(50):
+        while True:
             schemas_list = ", ".join(adapter.quote_string(s) for s in known_schemas)
             result = self._conn.query(adapter.find_downstream_schemas_sql(schemas_list))
             new_schemas = {row[0] for row in result} - known_schemas