test: Mark test_mcp_tools_in_inference as xfail due to deprecated registration API

The test requires register_tool_group() which is deprecated. The new approach
is configuration-based registration in run.yaml files under registered_resources.tool_groups.

Example NEW approach:
  registered_resources:
    tool_groups:
      - toolgroup_id: mcp::calculator
        provider_id: model-context-protocol
        mcp_endpoint:
          uri: http://localhost:3000/sse

The old dynamic registration API (register_tool_group) is marked deprecated with
no runtime replacement yet. Test should be updated to use config-based approach.

Author: Omar Abdelwahab

tests/integration/inference/test_tools_with_schemas.py

@@ -174,6 +174,10 @@ async def calculate(x: float, y: float, operation: str, ctx: Context) -> float:
         with make_mcp_server(required_auth_token=AUTH_TOKEN, tools={"calculate": calculate}) as server:
             yield server
 
+    @pytest.mark.xfail(
+        reason="Test uses deprecated register_tool_group() API. The new approach is configuration-based registration "
+        "in run.yaml under registered_resources.tool_groups. Test should be updated to use config-based approach."
+    )
     def test_mcp_tools_in_inference(self, llama_stack_client, text_model_id, mcp_with_schemas):
         """Test that MCP tools can be used in inference."""
         if not isinstance(llama_stack_client, LlamaStackAsLibraryClient):