defined a concrete process for scalability testing, created
documentation for the current scalability thresholds, and defined a new set of
Service Level Indicators (SLIs) and Service Level Objectives (SLOs) for the system.
Here's the release [scalability validation report].

[SIG Scalability]: https://github.com/kubernetes/community/tree/master/sig-scalability

- Deprecated the `apiserver_request_slo_duration_seconds` metric for v1.27 in favor of `apiserver_request_sli_duration_seconds` for naming consistency purposes with other SLI-specific metrics and to avoid any confusion between SLOs and SLIs. ([#112679](https://github.com/kubernetes/kubernetes/pull/112679), [@dgrisonnet](https://github.com/dgrisonnet))