test(rest): drive the tenancy axis of GET /ui/view/:object/:type

Extends PR #13244's measurement with the axis it explicitly did not assert:
its harness had no envRegistry and no kernelManager, so the environment
resolution chain was read from source and never driven.

Measurement only. rest-server.ts is untouched.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TvqBFLRzXdSPcbusDoED9k

Author: claude