Use custom namespace in ClusterRoleBinding if specified

[rowezuniga]

The ClusterRoleBinding should use a custom namespace if it's specified. If gremlin is configured with a custom namespace, the gremlin agent cannot fetch the node's topology zone/region labels and the log will show:

Before (can't fetch the node's metadata to fetch the zone/region information):

[WARN] gremlin_common::client::metadata::kube - Failed to get labels for Kubernetes node '<node>': nodes "<node>" is forbidden: User "system:serviceaccount:<custom-namespace>:gremlin" cannot get resource "nodes" in API group "" at the cluster scope: Forbidden. Check the permissions in the helm chart.

After (the zone/region tags are set):

Metadata set for [ zone: <zone> ]
Metadata set for [ region: <region> ]