Determine metrics to measure success of Scalability teams

The purpose of this issue is to discuss how we can measure the success of the Scalability teams' output. Having a small number of metrics will make it easier to understand what the core focus is for the group and whether we are moving in the right direction. The metrics will be closely aligned with the Performance Indicators for the Infrastructure department, but aim to specifically to highlight the things most important to Scalability.

Useful Links

• https://about.gitlab.com/handbook/engineering/infrastructure/performance-indicators/