Unrolled perf run results should include a link to the relevant PR

[Zalathar]

When doing unrolled perf runs to investigate regressions in a rollup, it would be helpful if the automated result post would include a link to the PR whose unrolled build is being tested. That would make it easier to keep track of which results correspond to which rolled-up PR.

Currently this has to be done manually, by checking prior comments or by looking up the commit hash in the table of unrolled builds.

E.g. see rust-lang/rust#145589 (comment), where I manually added the PR link afterwards.

(No idea how feasible this is at an implementation level.)

[Kobzol]

Hmm, I see the point, but from an implementation perspective that would be quite complicated. What I tend to do instead is to do the unrolled perf. runs on the PR itself (not on the rollup), I think that solves this issue and is generally better. It also allows to queue multiple unrolles perf. runs in parallel.

[Zalathar]

Yeah, I'm not surprised to hear that it would be unreasonably tricky. But I'm glad I asked.