Load service IDs from the YAML files

[bbockelm]

We currently have a list of service IDs in one of the YAML files:

https://github.com/opensciencegrid/topology/blob/master/topology/services.yaml

However, this is also duplicated here:

https://github.com/opensciencegrid/topology/blob/master/src/topology_utils.py#L112

We should consolidate it down to a single list of IDs.