Enrich cluster member struct with services and gRPC address.

[fmassot]

Description

Refactor a bit how we build cluster members and how we use it.

One benefit is that you can define the search client pool without depending on Cluster and thus Chitchat. This is nice for testing purposes. This will help me to test the upcoming MetastoreService.

How was this PR tested?

Waiting for make test-all results...