HTTP API error with Drop operation with Unexpected \""

This PR that changes the protobuf generation in the latest master branch broke the drop data request:

https://github.com/dgraph-io/dgraph/pull/7336

fde7e6421ded7046c01d4f3801be17ef8a2b2f84 is the first bad commit
commit fde7e6421ded7046c01d4f3801be17ef8a2b2f84
Author: Naman Jain <naman@dgraph.io>
Date:   Mon Jan 25 15:59:15 2021 +0530

    chore: update protos to use protoc-gen-gogofaster (#7336)

    With protoc-gen-gofast, we had some extra XXX_ fields. Using gogofaster removes these extra fields.

@Naman Can you look into this?

@bkennedy You can use Dgraph v20.11.1 version (latest) in the mean time.