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

* Load Maps on Round Start, not Round Restart

* Fix admin log test.
It assumed maps/grids existed during pre-round, wihch is not a valid assumption anymore after this PR.

* Shutdown server if round fails to start 5 times.

* Fix bugs with round starting flag.

* Make StartRound not async, synchronously get new round ID from DB.

* Handle StationId.Invalid in PickBestAvailableJob
Instead of crashing, return null.
SpawnPlayer will handle this by making the player an observer or returning them to the lobby.

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)