[llvm] Remove NumVisited (PR #80627)

[via llvm-commits]

AtariDreams wrote:

> @AtariDreams please can you work with @nikic to investigate the effect on compile time : https://llvm-compile-time-tracker.com/

Maybe I should find out when the returns diminish enough and set that as the limit
Across 32 changed tests, I have a delta of around 250 instructions saved.

https://github.com/llvm/llvm-project/pull/80627