Improves atmos even more.

* Adds AtmosCooldown to tiles, so they stop being active after a certain number of cycles without a cooldown reset.
* Fixes adjacentTileLength in ProcessCell. It wasn't being set beforehand, (probably) causing some incorrect air shares.
* Removing a tile from active tiles no longer unexcites every other tile in their excited group. (Basically, Dismantle in ExcitedGroup's Dispose() method no longer unexcites tiles)

Content.Server/Atmos/ExcitedGroup.cs

@@ -105,6 +105,7 @@ namespace Content.Server.Atmos
             {
                 if (tile?.Air == null) continue;
                 tile.Air.CopyFromMutable(combined);
+                tile.AtmosCooldown = 0;
                 tile.UpdateVisuals();
             }
 
@@ -131,7 +132,7 @@ namespace Content.Server.Atmos
             _disposed = true;
             _gridAtmosphereComponent.RemoveExcitedGroup(this);
 
-            Dismantle();
+            Dismantle(false);
 
             _gridAtmosphereComponent = null;
         }