telemetry: fix cert expiry metrics by removing labels
telemetry: fix cert expiry metrics by removing labels

These labels should be set by whatever process scrapes Consul (for
prometheus), or by the agent that receives them (for datadog/statsd).

We need to remove them here because the labels are part of the "metric
key", so we'd have to pre-declare the metrics with the labels. We could
do that, but that is extra work for labels that should be added from
elsewhere.

Also renames the closure to be more descriptive.

hashicorp/consul,hashicorp/consul,hashicorp/consul,hashicorp/consul