Remove some BUI boilerplate (#28399)

* Remove some BUI boilerplate

- The disposals overrides got removed due to the helper method handling it.
- Replace window creation with CreateWindow helper.
- Fixed some stinky code which would cause exceptions.

* More

* moar

* weh

* done

* More BUIs

* More updates

* weh

* moar

* look who it is

* weh

* merge

* weh

* fixes

Content.Client/Atmos/UI/GasCanisterBoundUserInterface.cs

@@ -1,6 +1,7 @@
 using Content.Shared.Atmos.Piping.Binary.Components;
 using JetBrains.Annotations;
 using Robust.Client.GameObjects;
+using Robust.Client.UserInterface;
 
 namespace Content.Client.Atmos.UI
 {
@@ -21,14 +22,8 @@ namespace Content.Client.Atmos.UI
         {
             base.Open();
 
-            _window = new GasCanisterWindow();
+            _window = this.CreateWindow<GasCanisterWindow>();
 
-            if (State != null)
-                UpdateState(State);
-
-            _window.OpenCentered();
-
-            _window.OnClose += Close;
             _window.ReleaseValveCloseButtonPressed += OnReleaseValveClosePressed;
             _window.ReleaseValveOpenButtonPressed += OnReleaseValveOpenPressed;
             _window.ReleasePressureSet += OnReleasePressureSet;