Removes some unused fields (#2603)

* removes some unused fields

* thats an oopsie

Co-authored-by: Paul <ritter.paul1+git@googlemail.com>
Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

Content.Client/GameObjects/EntitySystems/GasTileOverlaySystem.cs

@@ -24,8 +24,6 @@ namespace Content.Client.GameObjects.EntitySystems
         [Dependency] private readonly IMapManager _mapManager = default!;
         [Dependency] private readonly IResourceCache _resourceCache = default!;
 
-        private readonly Dictionary<float, Color> _fireCache = new();
-
         // Gas overlays
         private readonly float[] _timer = new float[Atmospherics.TotalNumberOfGases];
         private readonly float[][] _frameDelays = new float[Atmospherics.TotalNumberOfGases][];