Rename "Covered Experience SLIs" to avoid naming conflict with SLA terminology

Problem

We currently have a naming conflict between two different concepts that both use "Covered Experience" terminology:

  1. Covered Experiences (SLA context) - The specific GitLab features and services that are covered under our Service Level Agreement (Issues, Merge Requests, Git Operations, Container Registry, etc.)
  2. Covered Experience SLIs - Our observability metrics that measure user experience across different GitLab features, including those covered by the SLA

This naming collision creates confusion because they are closely related, but not the same.

Context

This issue was identified during the review of the unified Service Availability Definition for GitLab.com and Dedicated (see MR !15942).

As noted by @andrewn:

"Covered Experiences" is industry-standard SLA terminology, and we should follow that convention. However, this creates a confusing name clash with our "Covered Experience (SLIs)". In retrospect, calling the SLIs "Covered Experiences" was a mistake, and we should change them now before it becomes even more confusing.

Proposed Solution

Rename "Covered Experience SLIs" to "User Experience SLIs" to:

  • Eliminate the naming conflict with SLA "Covered Experiences"
  • Better reflect what these metrics actually measure (user experience)
  • Align with clearer, more descriptive terminology

Impact Assessment

This change will require updates to:

Acceptance Criteria

  • All references to "Covered Experience SLIs" are updated to "User Experience SLIs"
  • Documentation clearly distinguishes between SLA "Covered Experiences" and "User Experience SLIs"
  • Handbook design document is updated with new terminology
  • Labkit Ruby gem implementation is updated with new naming
  • No broken links or references remain after the rename
  • Team members are informed of the terminology change

Related Issues

Edited by Hercules Merscher