Reconcile rails by default and GraphQL first

I don't know what to do next exactly. But we definitely have to clean up the handbook because these two adjacent sections literally contradict each other: https://about.gitlab.com/handbook/engineering/#rails-by-default-vuejs-where-it-counts https://about.gitlab.com/handbook/engineering/#graphql-first

Reference to the graphQL MR: !26504 (merged)

So we need to reconcile this work.