Geo: Buffer large proxied payloads into a file and stream in chunks
Right now the push-to-secondary code buffers the entire payloads of the
git-receive-pack data into RAM, base-64 encodes it, and sends it to the primary. This can lead to high RAM usage.
We should consider:
- Creating a temporary file
- Using HTTP chunked-encoding to send the data in batches
This should probably be done in conjuction with moving the proxy functionality to Workhorse (https://gitlab.com/gitlab-org/gitlab-ee/issues/7405), but there's no reason it can't also be done in Unicorn.