SpringBoot Re-order route registration for GraphQL WebMvc / WebFlux

Re-order the route registrations for GraphQL requests so that the most commonly matched path is evaluated first.

The common case is valid POST requests to the graphql endpoint, so add that handler first; we found there is some overhead in the request predicate evaluation (see this issue), so while it may seem like a micro-optimization, it's a trivial change and can avoid evaluating some predicates in the common case.