Fix sinks and toilets not draining (#33691)

* Fix AutoDrain

Per the system comments, AutoDrain is designed to automatically move
puddles into the drain (like a floor drain). Drains without AutoDrain
are still supposed to gradually empty the buffer, but not remove puddles
(like sinks and toilets).

However, a logic error in the original implementation causes drains with
AutoDrain set to false to simply not work. Hence sinks never emptied.

* Update documentation

Content.Shared/Fluids/Components/DrainComponent.cs

@@ -27,8 +27,8 @@ public sealed partial class DrainComponent : Component
     public float Accumulator = 0f;
 
     /// <summary>
-    /// Does this drain automatically absorb surrouding puddles? Or is it a drain designed to empty
-    /// solutions in it manually? 
+    /// If true, automatically transfers solutions from nearby puddles and drains them. True for floor drains;
+    /// false for things like toilets and sinks.
     /// </summary>
     [DataField]
     public bool AutoDrain = true;