Switch to compatibility renderer, temporarily.

This seems to make the lighting SIGNIFICANTLY worse (both the colour
grading and the shadows) but it might work better on WebXR - test but
likely will revert.

Author: mgiuca

project.godot

@@ -117,7 +117,8 @@ common/enable_object_picking=false
 
 [rendering]
 
-renderer/rendering_method="mobile"
+renderer/rendering_method="gl_compatibility"
+renderer/rendering_method.mobile="gl_compatibility"
 anti_aliasing/quality/msaa_3d=1
 
 [xr]