ci: drop stale path_field_renames from mcp runner test constructor

#10176 removed `path_field_renames` from `EndpointTool`, while #10162 added a
new `ep()` test constructor in runner.rs that still set it. Each passed CI
against its own base, but together on main the test build fails with E0560.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/windmill-mcp/src/server/runner.rs

@@ -854,7 +854,6 @@ mod tests {
             path_params_schema: None,
             query_params_schema: None,
             body_schema: None,
-            path_field_renames: None,
             query_field_renames: None,
             body_field_renames: None,
         }