[llvm] [NFC][AMDGPU] Do not flush after printing every instruction (PR #95237)

[Ivan Kosarev via llvm-commits]

kosarev wrote:

> > Easy, but probably not ideal from performance and disk wearing perspectives.
> 
> Flushing too often - just because some tests aren't updated - is very likely way worse for performance (and your disk's lifespan).

Agree, we still should not flush on every instruction. It's just that there are probably better ways than writing to a file.

https://github.com/llvm/llvm-project/pull/95237