SignalFx FetchAllHostMetrics returns FQDN node names

[zorro786]

In FetchAllHostMetrics() method implementation by SignalFx client, the query is done to fetch all the metrics from SignalFx server with FQDNs, as added by SignalFx to Kubernetes node names. For example,

Node name like "test" is stored with its FQDN as "test.gcp.us-central.com". We would like to strip the node name from this.
We need a filter per cluster to avoid conflicts across clusters when we strip, and also for better query performance.