fix: Make traffic share dashboard load by default

This reduces the default range to the last 2 days instead of the last 7 days. Since loading 7 days often hits the boundary of how many samples we can load from Thanos.

While I was here, I also added the trailer linking to the repository to update the dashboard.

Snapshot: https://dashboards.gitlab.net/dashboard/snapshot/qmtogrjZg0le8XX84gBj9dObBflqKNvY?orgId=1