[ram_file.erl] read/2 issues

[tank-bohr]

https://github.com/erlang/otp/blob/34b56e8f566c6f1aa6023bb7b4096b8f2d709d9e/lib/kernel/src/ram_file.erl#L135-L162

1. Copy-paste is considered to be code smell
2. Calling GC while reading file can cause unpredictable latency