Leave jobs pending in fed when cluster is removed

When a cluster is removed from the federation, pending jobs should
remain pending.

1. If a job is pending on a origin cluster and the origin is being
removed then leave the pending job on the origin as a non-federated job
and remove the other sibling jobs.

2. If the job is viable on only one cluster than leave it as a pending
as non-federated job on the viable cluster.

3. If the origin cluster is being removed and the job is viable on
multiple clusters other than the origin then leave the sibling jobs as
federated job and the remainin viable clusters will schedule amongst
themselves to start the job.