Rename `NamespaceSettings::UpdateService`

The class NamespaceSettings::UpdateService does not actually updated namespace settings, it assigns attributes. See the behavior of attributes= vs update here.

The settings are persisted via a save to the namespace associated with the namespace settings (via Groups::UpdateService, which calls NamespaceSettings::UpdateService)

As a result, the name of this class is misleading, it does not actually perform an update. It should have a name that reflects is true behavior, something like NamespaceSettings::AssignAttributesService. Note that there is a regular version of this class and an EE version. Both versions should be renamed.

See related conversation here.