Replace `not connected` to `never contacted` for runner status

🧩 Problem

We use not connected in the database today to represent runners that have never connected to the instance. We also surface that as a status.

We also include a table column named Last contact that displays when the runner has last contacted GitLab. Finally, we use contact to describe runners that are online and offline. We should use the same terminology all around.

💡 Proposal

Update any statuses using connected to use contacted

• Case 1: not connected to never contacted