Fixes bug where the PlasmaFire reaction wouldn't reset reaction results properly.

This would cause the hotspot volume to grow more and more until the hotspot bypasses processing and therefore doesn't spread anymore.

Content.Server/Atmos/Reactions/PlasmaFireReaction.cs

@@ -19,6 +19,7 @@ namespace Content.Server.Atmos.Reactions
             var oldHeatCapacity = mixture.HeatCapacity;
             var temperature = mixture.Temperature;
             var location = holder as TileAtmosphere;
+            mixture.ReactionResults[GasReaction.Fire] = 0;
 
             // More plasma released at higher temperatures
             var temperatureScale = 0f;