Reduce 502 errors by increasing WriteTimeout to 10min

Created by: mrnugget

This adresses customer reports of 502 errors showing up in the UI.

I could easily reproduce the error message by putting a time.Sleep(65*time.Second) in the NewSearchImplementer code in the GraphQL backend.

That lead to the request running into the write timeout, which closes the connection after 60s without writing a byte on it. That in turn leads to nginx in front of frontend to respond with a 502 Bad Gateway.

I discussed this fix here with @keegancsmith and while we do think that we should fix the underlying problem (search is slow for customers) increasing this timeout also makes sense since customers might make non-search requests that take longer than 60s (downloading a zip file, for example?)