Fixes#486.
I finally figured out what the issue was: a missing `post-buffering` option to let Relay finish it's POST request for auth. This PR supersedes #543.
This patch adds `INTERNAL_IPS` definition to `sentry.conf.py` by sniffing the network from eth0 and relies on this for trusted Relays instead of the ALLOWLISTED PKs. This removes the necessity of syncing Relay PKs to `sentry.conf.py`.
This PR needs getsentry/sentry#19798 to work.
This patch brings back the HTTP/1.1 related settings for uWSGI to fix#486 as apparently Relay tries to talk to Sentry Web with keep alives where uWSGI terminates the connection unexpectedly. It also ports some configs for uWSGI and nginx from single-tenant.
Currently in sentry, both SnubaSearchBackend and EventsDatasetSnubaSearchBackend exist, and they are the same.
This just points to the new (renamed) class so we can delete SnubaSearchBackend from sentry, as we only left it in to transition getsentry & onpremise.
