Pin mcp<2 in agent-e2e

[ling-senpeng13]

mcp 2.0.0 removed mcp.server.fastmcp, which mcp-testkit still imports — the testkit died on import and test_suite4_mcp_tools.py failed collection. mcp was unpinned (transitive via claude-code-sdk).

Also probe the port instead of sleep 2, so a dead testkit fails its own step.

https://github.com/conductor-oss/python-sdk/actions/runs/31633373975/job/94237499406?pr=471

/opt/hostedtoolcache/Python/3.12.13/x64/lib/python3.12/site-packages/mcp_test_server/tools/echo_tools.py:5: in <module>
    from mcp.server.fastmcp.exceptions import ToolError
E   ModuleNotFoundError: No module named 'mcp.server.fastmcp'
- generated xml file: /home/runner/work/python-sdk/python-sdk/results/junit-e2e.xml -
=========================== short test summary info ============================
ERROR e2e/test_suite4_mcp_tools.py - ImportError while importing test module '/home/runner/work/python-sdk/python-sdk/e2e/test_suite4_mcp_tools.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/opt/hostedtoolcache/Python/3.12.13/x64/lib/python3.12/importlib/__init__.py:90: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
e2e/test_suite4_mcp_tools.py:52: in <module>
    EXPECTED_TOOL_NAMES = _expected_tools_from_source()
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^