[llvm] [CI] Make premerge_advisor_explain write comments (PR #166605)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> Build ID to the build where you found out that it was failing already you mean? Like "it's flaky at head (and here's the build that proves it)".

Yep, exactly.

https://github.com/llvm/llvm-project/pull/166605