Consider removing the configuration of server IDs from ReplicationDomain and ReplicationServer

Following OPENDJ-5839, where server IDs are mandatory in the global configuration, server IDs for domains and replication servers configuration objects are redundant.

There are many places where the code is impacted as server IDs are always read from the config, especially in the unit tests; dsreplication may also have side effects, as it uses the configuration framework, so in mixed topologies it may fail to work.