Eevee: Remove the Volumetric Render checkbox

This is to simplify the usage of Volumetrics.

Now it automatically detect if there is any Volumetric material in the
view and allocate the needed buffer if any.

release/scripts/startup/bl_ui/properties_render.py

@@ -241,11 +241,6 @@ class RENDER_PT_eevee_volumetric(RenderButtonsPanel, Panel):
     def poll(cls, context):
         return (context.engine in cls.COMPAT_ENGINES)
 
-    def draw_header(self, context):
-        scene = context.scene
-        props = scene.eevee
-        self.layout.prop(props, "use_volumetric", text="")
-
     def draw(self, context):
         layout = self.layout
         layout.use_property_split = True
@@ -253,8 +248,6 @@ class RENDER_PT_eevee_volumetric(RenderButtonsPanel, Panel):
         scene = context.scene
         props = scene.eevee
 
-        layout.active = props.use_volumetric
-
         col = layout.column(align=True)
         col.prop(props, "volumetric_start")
         col.prop(props, "volumetric_end")