fix \uFFFF printing regression

[pfgithub]

What does this PR do?

Fixes #15314, Fixes #15326

I'm not sure why it used to work in 1.1.24 yet - "\uFFFF" may have passed through directly, but "\uFFFF§" should have gone through the utf-16 path which had the same bug and yet it used to work

[robobun]

❌ @Jarred-Sumner, your commit 98b9772 has 13 failures in #6629:

test/js/bun/spawn/spawn-streaming-stdin.test.ts - 1 failing on 🐧 3.20 x64-baseline

test/package.json - timeout on 🐧 3.20 x64-baseline

test/integration/next-pages/test/dev-server.test.ts - 1 failing on 🐧 3.20 x64-baseline

test/integration/next-pages/test/dev-server.test.ts - 1 failing on 🐧 3.20 x64

test/v8/v8.test.ts - 22 failing on 🐧 3.20 aarch64

test/v8/v8.test.ts - 22 failing on 🐧 3.20 x64-baseline

test/v8/v8.test.ts - 22 failing on 🐧 3.20 x64

test/js/node/child_process/child_process.test.ts - 1 failing on 🐧 3.20 aarch64

test/js/node/child_process/child_process.test.ts - 1 failing on 🐧 3.20 x64-baseline

test/js/node/child_process/child_process.test.ts - 1 failing on 🐧 3.20 x64

test/cli/install/bun-link.test.ts - 4 failing on 🐧 3.20 aarch64

test/cli/install/bun-link.test.ts - 4 failing on 🐧 3.20 x64-baseline

test/cli/install/bun-link.test.ts - 4 failing on 🐧 3.20 x64

test/js/node/fs/fs-promises-writeFile-async-iterator.test.ts - 1 failing on 🐧 22.04 aarch64

test/cli/install/registry/bun-install-registry.test.ts - timeout on 🐧 22.04 x64

test/cli/install/registry/bun-install-registry.test.ts - timeout on 🐧 3.20 x64

test/js/web/timers/setTimeout.test.js - 1 failing on 🐧 22.04 x64

test/js/bun/http/serve.test.ts - segmentation fault on 🐧 22.04 aarch64

test/js/bun/http/serve.test.ts - segmentation fault on 🐧 3.20 aarch64

test/js/bun/http/serve.test.ts - segmentation fault on 🐧 3.20 x64-baseline

test/js/bun/http/serve.test.ts - segmentation fault on 🐧 3.20 x64

test/js/bun/http/serve.test.ts - 1 failing on 🍎 14 aarch64

test/js/bun/http/serve.test.ts - 1 failing on 🍎 14 x64

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 12 x64

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 11 x64-baseline

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 12 x64-baseline

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 11 x64

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 11 aarch64

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 22.04 x64

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 20.04 x64

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 20.04 x64-baseline

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 20.04 aarch64

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 3.20 aarch64

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 3.20 x64-baseline

test/js/node/test/parallel/fs-watch-recursive-linux-parallel-remove.test.js - 1 failing on 🐧 3.20 x64

test/integration/next-pages/test/next-build.test.ts - 1 failing on 🐧 22.04 x64

test/js/web/websocket/websocket-client.test.ts - 4 failing on 🪟 2019 x64