Fix test_pybind_implicit_prepare_cache for C-API CI

Two bugs fixed in the test:

1. Add close() method to _FakeResult — QueryResult.close() calls
   self._query_result.close() internally; the missing method caused
   AttributeError during teardown on C-API CI.

2. Fix _get_pybind_connection monkeypatch to store fake_pybind in
   self._py_connection — the bare lambda returned fake_pybind but
   never stored it, so Connection.close() never called
   fake_pybind_connection.close(), causing
   'assert fake_pybind_connection.closed is True' to fail.

The test runs on both pybind and C-API CI jobs. These changes ensure
it passes on C-API without affecting the pybind behavior.

Author: adsharma

test/test_pybind_implicit_prepare_cache.py

@@ -14,6 +14,9 @@ def isSuccess(self) -> bool:
     def hasNextQueryResult(self) -> bool:
         return False
 
+    def close(self) -> None:
+        return
+
 
 class _FakePreparedStatement:
     def __init__(self, query: str, parameters: dict[str, object]):
@@ -83,9 +86,13 @@ def fake_pybind_connection(monkeypatch: pytest.MonkeyPatch) -> _FakePybindConnec
         "init_connection",
         lambda self: setattr(self, "_connection", _FakeBackendConnection()),
     )
-    monkeypatch.setattr(
-        lb.Connection, "_get_pybind_connection", lambda self: fake_pybind
-    )
+
+    def _get_pybind_connection(self: lb.Connection) -> _FakePybindConnection:
+        if self._py_connection is None:
+            self._py_connection = fake_pybind
+        return self._py_connection
+
+    monkeypatch.setattr(lb.Connection, "_get_pybind_connection", _get_pybind_connection)
     return fake_pybind