Revert "Revert "Load Maps on Round Start, not Round Restart v3 (#6989)" (#6990)"

This reverts commit 4aa65b6708.

Fixed the deadlock bug on postgres.

Content.Server/GameTicking/GameTicker.JobController.cs

@@ -108,6 +108,9 @@ namespace Content.Server.GameTicking
         private string? PickBestAvailableJob(IPlayerSession playerSession, HumanoidCharacterProfile profile,
             StationId station)
         {
+            if (station == StationId.Invalid)
+                return null;
+
             var available = _stationSystem.StationInfo[station].JobList;
 
             bool TryPick(JobPriority priority, [NotNullWhen(true)] out string? jobId)