Vulkan: Unhide from behind developer extras

The GPU backend selection menu, used to select the Vulkan backend, was
hidden behind the Developer Extras user interface option in 4.3 as
Vulkan wasn't ready for wide spread testing due to multiple
major issues.

The majority of the major issues have been fixed, and Vulkan should
safer to use.

To help encourage Vulkan testing throughout Blender 4.4's development,
this commit unhides the Vulkan backend from behind the developer extras
option.

Pull Request: https://projects.blender.org/blender/blender/pulls/131231

scripts/startup/bl_ui/space_userpref.py

@@ -681,10 +681,7 @@ class USERPREF_PT_system_display_graphics(SystemPanel, CenterAlignMixIn, Panel):
     bl_label = "Display Graphics"
 
     @classmethod
-    def poll(cls, context):
-        if not context.preferences.view.show_developer_ui:
-            return False
-
+    def poll(cls, _context):
         import platform
         return platform.system() != 'Darwin'