Viewport: don't show look dev shader balls by default.

We will show these in the shading workspace by default, but for most new
3D viewports that you open these are not needed.

source/blender/blenloader/intern/versioning_280.c

@@ -1100,7 +1100,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
 						v3d->overlay.backwire_opacity = 0.5f;
 						v3d->overlay.normals_length = 0.1f;
-						v3d->overlay.flag = V3D_OVERLAY_LOOK_DEV;
+						v3d->overlay.flag = 0;
 					}
 				}
 			}

source/blender/editors/space_view3d/space_view3d.c

@@ -333,7 +333,6 @@ static SpaceLink *view3d_new(const ScrArea *UNUSED(sa), const Scene *scene)
 	v3d->shading.cavity_ridge_factor = 1.0f;
 	copy_v3_fl(v3d->shading.single_color, 0.8f);
 
-	v3d->overlay.flag = V3D_OVERLAY_LOOK_DEV;
 	v3d->overlay.wireframe_threshold = 0.5f;
 	v3d->overlay.bone_select_alpha = 0.5f;
 	v3d->overlay.texture_paint_mode_opacity = 0.8;