Update meta for Use cases and Case studies pages

Created by: elzannewentzel

Stakeholder: Product Marketing Request: The metadata for the following pages needs to be updated. We recently made copy updates on the pages( #5414 (closed)) and the meta also requires updating.

• https://about.sourcegraph.com/case-studies
• Case studies: Learn how engineering teams use Sourcegraph's code intelligence platform to understand, fix, and automate across their entire codebase.
• https://about.sourcegraph.com/use-cases Use cases: See how the most productive dev teams use Sourcegraph to build software you rely on. From improving code security to streamlining code reuse, our customers use Sourcegraph to solve big code problems.