chore(ext/node): strengthen scrypt regression test for 128-byte keylen

[divybot]

Summary

The existing log_n > 64 doesn't panic test, added with the AWS-LC scrypt
migration, was misnamed (it actually tests keylen=128 with default options,
not log_n > 64) and resolved its promise unconditionally — so a silent
failure inside the callback would not surface.

Replace it with two assertive tests against the original reproduction from
#27716:

• scrypt with 128-byte keylen matches Node runs both the async and sync APIs
  with keylen=128 and asserts the output matches Node.js's hash byte-for-byte.
• scrypt handles concurrent 128-byte keylen calls issues two scrypt calls in
  parallel (mirroring the original report's double panic) and verifies both
  callbacks fire cleanly with identical output.

The Node-compatible behavior itself was already implemented when scrypt
switched to AWS-LC's EVP_PBE_scrypt in #33773; this just hardens the
regression coverage so a future regression would be caught.

Closes denoland/orchid#353

Test plan

• dprint fmt clean
• deno lint --config tests/config/deno.json clean
• Expected hash verified to match Node.js's output and the stable Deno
  2.8.1 release
• CI: cargo test unit_node::crypto::crypto_scrypt_test