src: avoid `std::make_unique`

Work around https://github.com/nodejs/build/issues/1254, which
effectively breaks stress test CI and CITGM, by avoiding
`std::make_unique` for now.

This workaround should be reverted once that issue is resolved.

Refs: https://github.com/nodejs/build/issues/1254

PR-URL: https://github.com/nodejs/node/pull/20386


Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Matheus Marchini <matheus@sthima.com>