chore: remove /healthy endpoint comment that contained wrong information

I think the comment that I removed in this MR was copied from https://gitlab.developers.cam.ac.uk/uis/devops/iam/deploy-identity/-/blob/master/staff_identity.tf#L107. I checked the /healthy endpoint in the ucam-observe remote server (https://gitlab.developers.cam.ac.uk/uis/devops/ucam-observe/ucam-observe-remote-server/-/blob/main/ucam_observe_remote_server/main.py?ref_type=heads#L118) and that one does not contain a check that the service can connect to the underlying database. So we can remove this comment to avoid confusion.