API endpoints that need a particular service to get data from are registered next to this service (#2737). In /storage_proxy function there live some endpoints that work with config, so this PR moves them to the existing config.cc with config-related endpoints. The path these endpoints are registered with remains intact, so some tweak in proxy API registration is also here.
Closesscylladb/scylladb#19417
* github.com:scylladb/scylladb:
api: Use provided db::config, not the one from ctx
api: Move some config endpoints from proxy to config
api: Split storage_proxy api registration
api: Unset config endpoints