[llvm] [nfc][docs]Generalize header and ascii art for indexed profiles (PR #83507)

[Mingming Liu via llvm-commits]

minglotus-6 wrote:

I think the doc is easier to maintain by removing boilerplates. Otherwise it's painful to update ascii art graph with templated content.

Planned to submit this change before https://github.com/llvm/llvm-project/pull/83309.


https://github.com/llvm/llvm-project/pull/83507