test(metadata-protocol): drop the duplicated PKG constant from the copied harness

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012zGPuVVX3deAx9LdjK8jCk

Author: os-try2026

packages/metadata-protocol/src/protocol-publish-drafts-object-field-refs.test.ts

@@ -179,7 +179,6 @@ function makeStubEngine() {
     return { engine, rows, historyRows };
 }
 
-const PKG = 'app.ops';
 const PKG = 'app.studio';
 
 /**