Reduce number of AWS API calls in ELB metrics collector (#1308)
Reduce number of AWS API calls in ELB metrics collector (#1308)

Instead of getting tags for each ELB separately group all ELB names into
one elb.DescribeTags query and work from there on.

ELB instance health stauses are still fetched with N requests because
AWS SDK doesn't allow specification of ELB names in
elb.DescribeInstanceHealthInput.

giantswarm/aws-operator,giantswarm/aws-operator