Remove default environment

Useless in 2D.

default_env.tres

@@ -1,7 +0,0 @@
-[gd_resource type="Environment" load_steps=2 format=2]
-
-[sub_resource type="ProceduralSky" id=1]
-
-[resource]
-background_mode = 2
-background_sky = SubResource( 1 )

project.godot

@@ -130,4 +130,3 @@ p7_right={
 quality/intended_usage/framebuffer_allocation=0
 quality/intended_usage/framebuffer_allocation.mobile=0
 quality/2d/use_pixel_snap=true
-environment/default_environment="res://default_env.tres"