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.Shared/CCVar/CCVars.cs

@@ -60,6 +60,9 @@ namespace Content.Shared.CCVar
         public static readonly CVarDef<bool>
             EventsEnabled = CVarDef.Create("events.enabled", true, CVar.ARCHIVE | CVar.SERVERONLY);
 
+        /// <summary>
+        ///     Disables most functionality in the GameTicker.
+        /// </summary>
         public static readonly CVarDef<bool>
             GameDummyTicker = CVarDef.Create("game.dummyticker", false, CVar.ARCHIVE | CVar.SERVERONLY);
 
@@ -154,6 +157,15 @@ namespace Content.Shared.CCVar
         public static readonly CVarDef<int> SoftMaxPlayers =
             CVarDef.Create("game.soft_max_players", 30, CVar.SERVERONLY | CVar.ARCHIVE);
 
+#if EXCEPTION_TOLERANCE
+        /// <summary>
+        ///     Amount of times round start must fail before the server is shut down.
+        ///     Set to 0 or a negative number to disable.
+        /// </summary>
+        public static readonly CVarDef<int> RoundStartFailShutdownCount =
+            CVarDef.Create("game.round_start_fail_shutdown_count", 5, CVar.SERVERONLY | CVar.SERVER);
+#endif
+
         /*
          * Discord
          */