Podman: Update podman-restart.service Description

Problem

The podman-restart.service description didn't mention that it restarts containers with unless-stopped restart policy, only mentioning always. This was changed in PR #27619 but the description wasn't updated.

Solution

Updated the service description to reflect the full restart behavior, including containers with unless-stopped policy.

Result

Service description accurately describes the restart behavior. No functional change.

Commit: containers/podman@f0dd315
Issue: #27908