chore(mcp): drop the protocol-version guard test

Removes tests/agent/tools/test_mcp/test_protocol_version.py. It pinned task-type imports
(CreateTaskResult / TaskMetadata) and the 2025-11-25 constant — assumptions the
long-running-job design has moved away from: the chosen _meta-based contract doesn't use
the SDK task types (which 2.x removes anyway). The version bump stands on the rest of the
mcp suite.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: edis-uipath