chore(tests): retire unused heuristic test-deletion report

The human-run packages/scripts/triage-tests.mjs reports KEEP/DELETE/CONVERT using directory names, filename infixes, runtime imports and mock density. These classifications do not establish whether a test protects an observable consumer failure: a useful mocked service test can be labelled DELETE while a metadata-only test in a test directory is labelled KEEP. That is misleading guidance for maintainers performing the current test simplification.

Full source and tracked-reference review on develop finds no executable callers. The only outside references are the audit-scripts.mjs human-run allowlist entry and .gitignore entries for its generated reports. The tool is already removed in broader refactor commit a5d4c10e66, but that deletion has not reached develop.

Scope: remove the obsolete script and its dedicated allowlist/report-ignore entries without importing the broader refactor or adding a replacement classifier. Preserve all actual test runners and discovery metadata.

Acceptance: no tracked callers or dangling references; script audit and its self-test pass; root verification passes; PR contains only the retirement and directly orphaned configuration. No replacement tests are needed for removal of this uncalled advisory report generator.