Fix errorRate metric for kas
Relates to gitlab-com/gl-infra/production#5407 (closed).
What this MR does:
- Excludes more codes from error rate metric. We were missing some that do not indicate issues with the server, but rather issues with the client's request. Gitaly also excludes them.
- Includes all server methods. Currently only
GetConfiguration
was measured. I think we need to look at all exposed API methods on all ports.