While all programatically constructed test configs will be v3 (via API boosting rewriting), there are still v2 JSON/YAML fragments in test code. Many of these will "just work" as v3, but some may have v2 features that will have them treated as v2. This becomes confusing when they are extended by developers who want to model v3 features.

These need to be audited and updated as appropriate. Also, the names of methods such as parseAccessLogFromV2Yaml should be updated to reflect v3 when operating on fragments that should be v3.

This is somewhat similar to the work done by @dmitri-d for examples in #10644 as part of #9735.

CC @alyssawilk