Naming convention does not correctly affect enums in relay endpoint

### Version Information

Server Version: v2.10.1

### Environment

OSS

### What is the current behaviour?

The [experimental `graphql-default` naming convention](https://hasura.io/docs/latest/schema/postgres/naming-convention) modifies enum variants:

> Enum values will be upper-cased. i.e. for an enum table, all the values will be upper-cased when used as enum value in Hasura Server.

This behavior does not carry over to the [relay api](https://hasura.io/docs/latest/api-reference/relay-graphql-api/index/).

### What is the expected behaviour?

Enum values in relay endpoint should be affected by the naming convention.

### How to reproduce the issue?

1. use the `graphql-default` naming convention
```env
HASURA_GRAPHQL_EXPERIMENTAL_FEATURES: naming_convention
HASURA_GRAPHQL_DEFAULT_NAMING_CONVENTION: graphql-default
```
2. enum values on the `/v1/graphql` endpoint are uppercased
3. enum values on the `/v1beta1/relay` endpoing are not uppercased