Move DevOps Score out of instance statistics

Overview

With #196455 (closed) and #196454 (closed), we can start hiding Instance Statistics in the top navbar when this feature's admin-only.

We're not confident that Instance Statistics, as currently displayed in the navbar, is the right place for these features to thrive. We should consider moving them elsewhere or refactor the Instance Statistics area into a more useful tool.

Proposal

• Move DevOps Score to the admin Analytics area (#233833 (closed)).
• Update the documentation for how to navigate to DevOps Score.