Code Cleanup: Purge obsolete MapManager methods (#26279)

* GetGrid

* GridExists

* TryGetGrid

Content.Server/Shuttles/Systems/ShuttleSystem.FasterThanLight.cs

@@ -559,7 +559,7 @@ public sealed partial class ShuttleSystem
 
     private float GetSoundRange(EntityUid uid)
     {
-        if (!_mapManager.TryGetGrid(uid, out var grid))
+        if (!TryComp<MapGridComponent>(uid, out var grid))
             return 4f;
 
         return MathF.Max(grid.LocalAABB.Width, grid.LocalAABB.Height) + 12.5f;