Remove constrained view in the 2D editor

We initially added an option to disable constraining the 2D editor view.
This setting was still enabled by default to avoid confusing users
who end up scrolling too far away from their current scene
(which is a problem if you don't know about the F key to focus
on the selection).

However, it's probably a better choice to unconstrain the 2D editor view
by default because:

- Lots of people don't know about this setting and wonder how they
  can scroll far away from the scene. This feels really limiting for them,
  and it can even lead to some people thinking Godot intentionally limits
  scene sizes.
- The 3D editor doesn't have such a contrain mechanism.
  This makes the 2D editor more consistent with the 3D editor.

doc/classes/EditorSettings.xml

@@ -228,9 +228,6 @@
 		<member name="editors/2d/bone_width" type="int" setter="" getter="">
 			The bone width in the 2D skeleton editor (in pixels). See also [member editors/2d/bone_outline_size].
 		</member>
-		<member name="editors/2d/constrain_editor_view" type="bool" setter="" getter="">
-			If [code]true[/code], prevents the 2D editor viewport from leaving the scene. Limits are calculated dynamically based on nodes present in the current scene. If [code]false[/code], the 2D editor viewport will be able to move freely, but you risk getting lost when zooming out too far. You can refocus on the scene by selecting a node then pressing [kbd]F[/kbd].
-		</member>
 		<member name="editors/2d/grid_color" type="Color" setter="" getter="">
 			The grid color to use in the 2D editor.
 		</member>

editor/editor_settings.cpp

@@ -687,7 +687,6 @@ void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 	_initial_set("editors/2d/bone_outline_color", Color(0.35, 0.35, 0.35, 0.5));
 	_initial_set("editors/2d/bone_outline_size", 2);
 	_initial_set("editors/2d/viewport_border_color", Color(0.4, 0.4, 1.0, 0.4));
-	_initial_set("editors/2d/constrain_editor_view", true);
 
 	// Panning
 	// Enum should be in sync with ControlScheme in ViewPanner.

editor/plugins/canvas_item_editor_plugin.cpp

@@ -4009,48 +4009,23 @@ void CanvasItemEditor::_update_scrollbars() {
 	canvas_item_rect.size += screen_rect * 2;
 	canvas_item_rect.position -= screen_rect;
 
-	// Constraints the view offset and updates the scrollbars.
-	Size2 size = viewport->get_size();
-	Point2 begin = canvas_item_rect.position;
-	Point2 end = canvas_item_rect.position + canvas_item_rect.size - local_rect.size / zoom;
-	bool constrain_editor_view = bool(EDITOR_GET("editors/2d/constrain_editor_view"));
+	// Updates the scrollbars.
+	const Size2 size = viewport->get_size();
+	const Point2 begin = canvas_item_rect.position;
+	const Point2 end = canvas_item_rect.position + canvas_item_rect.size - local_rect.size / zoom;
 
 	if (canvas_item_rect.size.height <= (local_rect.size.y / zoom)) {
-		real_t centered = -(size.y / 2) / zoom + screen_rect.y / 2;
-		if (constrain_editor_view && ABS(centered - previous_update_view_offset.y) < ABS(centered - view_offset.y)) {
-			view_offset.y = previous_update_view_offset.y;
-		}
-
 		v_scroll->hide();
 	} else {
-		if (constrain_editor_view && view_offset.y > end.y && view_offset.y > previous_update_view_offset.y) {
-			view_offset.y = MAX(end.y, previous_update_view_offset.y);
-		}
-		if (constrain_editor_view && view_offset.y < begin.y && view_offset.y < previous_update_view_offset.y) {
-			view_offset.y = MIN(begin.y, previous_update_view_offset.y);
-		}
-
 		v_scroll->show();
 		v_scroll->set_min(MIN(view_offset.y, begin.y));
 		v_scroll->set_max(MAX(view_offset.y, end.y) + screen_rect.y);
 		v_scroll->set_page(screen_rect.y);
 	}
 
 	if (canvas_item_rect.size.width <= (local_rect.size.x / zoom)) {
-		real_t centered = -(size.x / 2) / zoom + screen_rect.x / 2;
-		if (constrain_editor_view && ABS(centered - previous_update_view_offset.x) < ABS(centered - view_offset.x)) {
-			view_offset.x = previous_update_view_offset.x;
-		}
-
 		h_scroll->hide();
 	} else {
-		if (constrain_editor_view && view_offset.x > end.x && view_offset.x > previous_update_view_offset.x) {
-			view_offset.x = MAX(end.x, previous_update_view_offset.x);
-		}
-		if (constrain_editor_view && view_offset.x < begin.x && view_offset.x < previous_update_view_offset.x) {
-			view_offset.x = MIN(begin.x, previous_update_view_offset.x);
-		}
-
 		h_scroll->show();
 		h_scroll->set_min(MIN(view_offset.x, begin.x));
 		h_scroll->set_max(MAX(view_offset.x, end.x) + screen_rect.x);