Update api.nasqueron.org API configuration

Summary:
Use upstream blocks to define servers, so if we need HA for a service,
it will be trivial to add it here.

API backends are defined through private Drake network.

This is a follow-up for 6f2bfa2bab99.

Ref T1779

Test Plan:
Tested on Ysul.

• Browse https://api.nasqueron.org/datasources
• Browse https://api.nasqueron.org/docker/registry/stats

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1779

Differential Revision: https://devcentral.nasqueron.org/D2827