This table purposefully does not index by partition/namespace. It's a
global view into all service names.
This table is intended to replace the current serviceListTxn watch in
intentionTopologyTxn. For cross-partition transparent proxying we need
to be able to calculate upstreams from intentions in any partition. This
means that the existing serviceListTxn function is insufficient since
it's scoped to a partition.
Moving away from that function is also beneficial because it watches the
main "services" table, so watchers will wake up when any instance is
registered or deregistered.
497aab669f