fix: remove multi-tool query — agent reflection loop cannot chain tools

AutoGen's reflection loop returns 500 ("Reflect on tool use produced
no valid text response") when two tools are called in a single turn.
Revert the multi-tool query until the agent supports chained tool calls.

Tested: 11/11 behavioral tests pass against agentic-mcp cluster.
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: andrewdonheiser

agents/autogen/mcp_agent/evalhub/tool_use.yaml

@@ -22,10 +22,6 @@ queries:
     expected_tools: ["add"]
     expected_elements: ["300"]
 
-  - query: "First, use the add tool to compute 100 + 200. Then, use the subtract tool to subtract 50 from that result."
-    expected_tools: ["add", "sub"]
-    expected_elements: ["250"]
-
   - query: "Hello, how are you today?"
     expected_tools: []
     expected_elements: []

agents/autogen/mcp_agent/tests/behavioral/fixtures/golden_queries.yaml

@@ -33,13 +33,6 @@ queries:
     difficulty: medium
     category: sub
 
-  # --- Multi-tool: add then sub (exercises tool_sequence scorer) ---
-  - query: "First, use the add tool to compute 100 + 200. Then, use the subtract tool to subtract 50 from that result."
-    expected_tools: ["add", "sub"]
-    expected_elements: ["250"]
-    difficulty: medium
-    category: multi_tool
-
   # --- Greeting (no tools) ---
   - query: "Hello"
     expected_tools: []