Promote unchanged module mock corpus workflows

Remove the remaining source rewrites for the Bun module-mocking workflows now supported by the full native VM.

Scope:

• delete rewriteMockModuleLiveReexportCorpus for js/bun/test/mock/6879/6879.test.ts
• delete rewriteMockModuleCorpus for js/bun/test/mock/mock-module.test.ts
• route both copied files unchanged through the native test runner
• retain exact Bun fixture bytes and upstream TODO accounting

Baseline at Bun 4982b91 and current Home Debug strict mode:

• 6879.test.ts: 2 pass, 0 fail
• mock-module.test.ts: 9 pass, 1 upstream TODO, 0 fail

Acceptance includes Debug and ReleaseSafe routed plus strict verification.

Implementation pushed in c33a265.

Removed rewriteMockModuleLiveReexportCorpus and rewriteMockModuleCorpus entirely, then routed both unchanged files through the full native test runner.

Debug evidence:

• js/bun/test/mock/6879/6879.test.ts: strict 2 pass / 0 fail; routed 2 pass / 0 fail / 0 TODO / 0 unsupported
• js/bun/test/mock/mock-module.test.ts: strict 9 pass / 1 upstream TODO / 0 fail; routed 9 pass / 1 upstream TODO / 0 fail / 0 unsupported
• pinned Bun reports the same totals
• both copied files are SHA-256 identical to Bun 4982b91
• Debug build and format/diff checks pass

ReleaseSafe remains pending because a separate root-checkout full suite is still consuming nearly all free disk. The issue stays open until that verification completes.

Completed by c33a265 and verified again in the ReleaseSafe artifact built at 11a7bcc.

Final acceptance:

• Debug and ReleaseSafe builds pass
• unchanged 6879.test.ts: 2 pass, 0 fail
• unchanged mock-module.test.ts: 9 pass, 1 upstream TODO, 0 fail
• combined ReleaseSafe routed run: 11 pass, 1 TODO, 0 fail, 0 unsupported
• combined ReleaseSafe strict run: identical accounting
• copied fixture hashes remain byte-identical to Bun

Both source rewrites are gone; no fixture or assertion was changed.