Record latency apdex per feature category for rails
This contains a rudimentary apdex calculation for puma request latency, with 1s as the satisfied trheshold.
The threshold is "copied" over from the puma-component for the service from the metrics catalog.
This is a spike of the solve for 1a in gitlab-com/gl-infra/scalability#888
Edited by Bob Van Landuyt