src: avoid deferred gc/cleanup for Buffer.from

Previously, the code path would allocated a tracked ArrayBuffer
that defers cleanup and deallocation of the underlying data with
a SetImmediate. Avoid the unnecessary deferral by just allocating
a `BackingStore` directly and writing into it.

Fixes: https://github.com/nodejs/node/issues/38300
Refs: https://github.com/nodejs/node/pull/38336

PR-URL: https://github.com/nodejs/node/pull/38337


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Khaidi Chu <i@2333.moe>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>