Disable [message] blurring once again pending further testing

There are certain performance issues with scrolling lists with this enabled
that would render this unusable even without the weird hover bug (#24667).

data/gui/widget/panel_wml_message.cfg

@@ -20,7 +20,10 @@
 
 			[draw]
 
-				{DEFAULT_BLUR}
+				# This works fine for normal messges. However, messages with options behave
+				# strangely, and messages with scrollbars perform badly.
+				# Uncomment once this has been fixed.
+				#{DEFAULT_BLUR}
 
 				[image]
 					x = 0