chore: crosslink labkit issue from blueprint

chore: crosslink labkit issue from blueprint

This crosslinks an issue in which we've recently started discussing the direction of Labkit. I think it makes sense to crosslink it from this blueprint.

This also updates the wording from "strongly encouraged" to "Required" in the description column, since we're already saying that in the required column.

For Ruby and Go, we can already require this, there should be some stuff we get by default (correlation & metrics), and this can grow in the future. For Python we'll need to get something prepared.

Related to gitlab-com/gl-infra/scalability#2793