[Tweak] Janibucket buffs (#15422)

* Improves Janitor trolley significantly by adding bucket slot with sprite overlay, and 300 extra water capacity. Improves Janitor bucket slightly by adding 100 extra water capacity.

* Reduces janitor trolley density by 100 to it's pull a bit faster

Resources/Textures/Objects/Specific/Janitorial/janitorial_cart.rsi/meta.json

@@ -19,6 +19,10 @@
             "name": "cart_mop",
             "directions": 4
         },
+        {
+            "name": "cart_bucket",
+            "directions": 4
+        },
         {
             "name": "cart_replacer",
             "directions": 4
@@ -122,4 +126,4 @@
             ]
         }
     ]
-}
+}