[astute] too verbose dump of nodes data during nodes removing

https://github.com/openstack/fuel-astute/blob/stable/mitaka/lib/astute/nodes_remover.rb#L75

Leads to way verbose dump of nodes. It looks that just logging of uids would be enough.

Eg.:

Split nodes: {}, {"5"=>#<Astute::Node profile="ubuntu_1404_x86_64", name_servers_search="\"domain.tld\"", uid="5", interfaces={"eth3"=>{"static"=>"0", "mac_address"=>"52:54:00:07:51:aa"}, "eth2"=>{"static"=>"0", "mac_address"=>"52:54:00:3f:ee:ba"}, "eth1"=>{"static"=>"0", "mac_address"=>"52:54:00:70:27:ea"}, "eth0"=>{"ip_address"=>"10.21.23.91", "dns_name"=>"node-5.domain.tld", "netmask"=>"255.255.0.0", "static"=>"0", "mac_address"=>"52:54:00:1a:bc:7a"}}, interfaces_extra={"eth3"=>{"onboot"=>"no", "peerdns"=>"no"}, "eth2"=>{"onboot"=>"no", "peerdns"=>"no"}, ... Continues