Only allow documented token types for GraphQL authentication

What does this MR do and why?

Only allow documented token types for GraphQL authentication

Currently, some token types besides those documented in the Token authentication section of the GraphQL docs can be used to authenticate a user for GraphQL. This MR ensures that only the documented token types are usable, once the associated feature flag is enabled.

Further context and discussion here (private link)

MR acceptance checklist

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Before	After

How to set up and validate locally

1. Set up a project locally with git lfs
2. enable the feature on the Rails console: Feature.enable(:graphql_minimal_auth_methods)
3. Get an LFS token via the ssh interface: ssh -p 2222 git@<LOCAL_HOSTNAME> git-lfs-authenticate <NAMESPACE>/<PROJECT_NAME>.git download
4. Copy the token from the "header":{"Authorization":"Basic <COPY_THIS_TOKEN> section
5. Make a GraphQL request to http(s)://<HOSTNAME>:<PORT>/api/graphql.git using the token in the Authorization: Basic <COPIED_TOKEN> header:
   curl -X "POST" "http://localhost:3000/api/graphql.git" -H 'Content-Type: application/json; charset=utf-8' -u 'USERNAME:COPIED_TOKEN' -d $'{"query": "query{currentUser{id username}}","variables": {}}'
6. The request should no longer be authenticated; currentUser should return null and restricted resources should not be accessible.

Related to #442520