Remove simplified test_instance_data port

The upstream test verifies finalizer and environment teardown behavior
via subprocesses and worker threads, not just increment(). The simplified
CTS port lost that coverage, so remove it and reclassify as Medium.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: kraenhansen

PORTING.md

@@ -60,7 +60,7 @@ Tests covering the engine-specific part of Node-API, defined in `js_native_api.h
 | `test_function`              | Not ported | Medium     |
 | `test_general`               | Not ported | Hard       |
 | `test_handle_scope`          | Ported ✅  | Easy       |
-| `test_instance_data`         | Ported ✅  | Easy       |
+| `test_instance_data`         | Not ported | Medium     |
 | `test_new_target`            | Ported ✅  | Easy       |
 | `test_number`                | Ported ✅  | Easy       |
 | `test_object`                | Not ported | Hard       |