Fix BatchLoader deprecation warnings

What does this MR do and why?

With this MR we're fixing the deprecation warnings by replacing BatchLoader.for with BatchLoader::GraphQL.for 🎉

References

• #322978

Screenshots or screen recordings

N/A

How to set up and validate locally

1. Checkout the branch
2. Verify there are no more BatchLoader.for instances locally 🎉

MR acceptance checklist

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