[Bench] Add stats for benchmark executions in GHA summary

[lukaszstolarczuk]

No description provided.

[lukaszstolarczuk]

example summaries:

• (all passed) https://github.com/intel/llvm/actions/runs/19372212987#summary-55430718435
• (simulated fails) https://github.com/intel/llvm/actions/runs/19373442898#summary-55434864295
• (simulated suite fails) https://github.com/intel/llvm/actions/runs/19370309208

[pbalcer]

Hm, I think it might be better to move this to its own file, like we do for generating markdown and html. Btw, can't we use the existing markdown for this? Even if we simplify it.