Sunset non-Subgraph backwards compatible GraphQL API endpoints

[lightwalker-eth]

Goals

• Reduce the surface area of APIs we'll be investing in moving forward. We want to maximize the focus of our investments in building new REST-based APIs (non-autogenerated GraphQL).

Subtasks

• Support apps like https://www.ensvolution.xyz/ that are already live in production and relying on the /ponder endpoint to transition to our /graphql endpoint.
• Fully remove the /ponder GraphQL endpoint.