this setting was removed back in
dcdd207349, so despite that we are still
passing `storage_service_config` to the ctor of `storage_service`,
`storage_service::storage_service()` just drops it on the floor.
in this change, `storage_service_config` class is removed, and all
places referencing it are updated accordingly.
Signed-off-by: Kefu Chai <tchaikov@gmail.com>
Closes #11415