x/build: add "slowbots" support #34501
We aim to make TryBots be only 5 minutes, but sometimes people want long, deeper tests over all architectures.
We've heard from the compiler/runtime team (@martisch, et al) that a more broad TryBot mode would be useful.
I thought we had a bug for this already but can't find it. (Maybe it was a comment on another bug)
The plan I thought writing about elsewhere was that when clicking "+1 TryBot", you could write some magic syntax in the comment field on Gerrit to specify which extra bots run. Some other tool can help you construct that magic comment & do the Gerrit comment for you, like git-codereview does (when you specify