[v14.x backport] fs: improve fsPromises readFile performance

[Linkgoron]

Improve the fsPromises readFile performance
by allocating only one buffer, when size is known,
increase the size of the readbuffer chunks,
and dont read more data if size bytes have been read

refs: #37583

PR-URL: #37608

I only cherry-picked the changes to fs/promises.js (first commit) but didn't backport the benchmark (second commit). If that's needed, I'll be happy to do it as well. This PR also incorporates the changes of #37127, so I'm not sure if that PR should be backported before this one.

[Linkgoron]

Benchmark numbers:

 confidence improvement accuracy (*) (**) (***) fs/readfile-promises.js concurrent=1 len=1024 duration=5 *** 24.56 % ±0.52% ±0.69% ±0.90% fs/readfile-promises.js concurrent=1 len=16777216 duration=5 *** 353.44 % ±4.88% ±6.56% ±8.68% fs/readfile-promises.js concurrent=10 len=1024 duration=5 *** 30.64 % ±0.58% ±0.78% ±1.02% fs/readfile-promises.js concurrent=10 len=16777216 duration=5 *** 573.13 % ±4.38% ±5.89% ±7.78% 

[Linkgoron]

Noticed that this needs to wait for two weeks.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/36949/

[Linkgoron]

@targos given the AbortController PR, this (the original PR) might land cleanly without any modifications after #35911 is backported.

[targos]

This PR is actually what started my quest of backporting AbortController 😄