api/server: Do not read configuration at each request
This is more performant but also avoids cluttering the logs of the service in production.
The counterpart is it allows less dynamicity during the change of configuration.
This is equivalent to what has been done in the scheduler [1]
- [1] rDSCHc701c8823b694aed7ce5795ceca6efd5ac6c1fa5
Test Plan
tox
Migrated from D1128 (view on Phabricator)