Add log when a player starts observing. (#26091)

(cherry picked from commit 85e0a5328a28b02fc29575648cfa7421f5bfb410)

Content.Server/GameTicking/GameTicker.Spawning.cs

@@ -346,6 +346,7 @@ namespace Content.Server.GameTicking
             _metaData.SetEntityName(ghost, name);
             _ghost.SetCanReturnToBody(ghost, false);
             _mind.TransferTo(mind.Value, ghost);
+            _adminLogger.Add(LogType.LateJoin, LogImpact.Low, $"{player.Name} late joined the round as an Observer with {ToPrettyString(ghost):entity}.");
         }
 
         #region Mob Spawning Helpers