test: update mock assertions for conversation_history kwarg

The /branch and /resume flush tests asserted the old positional-only
call signature. Update to match the fix from #68480.

tests/cli/test_branch_command.py

@@ -256,5 +256,6 @@ class TestBranchFlushesBeforeEndSession:
         HermesCLI._handle_branch_command(cli_instance, "/branch")
 
         agent._flush_messages_to_session_db.assert_called_once_with(
-            cli_instance.conversation_history
+            cli_instance.conversation_history,
+            conversation_history=cli_instance.conversation_history,
         )

tests/cli/test_cli_resume_command.py

@@ -421,6 +421,7 @@ class TestResumeFlushesBeforeEndSession:
             cli_obj._handle_resume_command("/resume target")
 
         agent._flush_messages_to_session_db.assert_called_once_with(
-            [{"role": "user", "content": "hello"}, {"role": "assistant", "content": "hi"}]
+            [{"role": "user", "content": "hello"}, {"role": "assistant", "content": "hi"}],
+            conversation_history=[{"role": "user", "content": "hello"}, {"role": "assistant", "content": "hi"}],
         )
         cli_obj._session_db.end_session.assert_called_once()