Discussion.json perform over 800 Gitaly RPC requests

Example for gitlab.com: api/v4/projects/13083/merge_requests/23464/discussions, but also the discussion.json on the MR view will show a very large number of Gitaly requests in the performance bar.

On the logs this specific MR came by a few times and each time it had close to 800 Gitaly RPC's. When visiting the MR itself the performance bar showed closer to 1000 requests on Gitaly, most of which are FindCommit RPC's for the same commit too.

The MR itself is relatively large, but this should never create so many Gitaly RPC calls.