Potentially tweak at instance caps for Jenkins agent types

[Cervator]

During my initial sweet to CaC the Jenkins build agents I couldn't find a good variable in Helm that would work for setting the instance cap per agent which we used in the past. There's still a default overall cap on the amount of builder pods that should be enough for now, and we don't really need the level of granularly from the past anyway, not yet at least. The diversity in the pods, labels, and resource config has been collapsed a fair bit over time.