[llvm] [docs] use `=` in `--max-retries-per-test=N` (PR #142340)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

It seems like the docs use a mix of both styles -- should we normalize to one or the other for *all* options?

https://github.com/llvm/llvm-project/pull/142340