Do not refresh data on filtering stuff by cluster

Listing nodes of node groups downloads all data from
Nailgun so there is no need to refresh it during the
following filtering by cluster id.

Closes-bug: #1378963
Change-Id: Ib9f45225f6e3c91809ea0dbc47e79b3529b54d3b
Merge "Do not refresh data on filtering stuff by cluster"