Use old reagent dispenser beaker slot ID (#24209)

Change the slot ID back to what it was to keep old map saves with an item in the slot loading correctly.

This also fixes the "You can't put this in the dispenser!" message not appearing when inserting an item without FitsInDispenserComponent because the whitelisted slot name wasn't changed.

Content.IntegrationTests/Tests/Chemistry/DispenserTest.cs

@@ -25,7 +25,7 @@ public sealed class DispenserTest : InteractionTest
         await Interact();
 
         // Eject beaker via BUI.
-        var ev = new ItemSlotButtonPressedEvent(ReagentDispenserComponent.BeakerSlotId);
+        var ev = new ItemSlotButtonPressedEvent(SharedReagentDispenser.OutputSlotName);
         await SendBui(ReagentDispenserUiKey.Key, ev);
 
         // Beaker is back in the player's hands