Revert "scene: ignore outputs with too small intersection with nodes"

This reverts commit 95b2771bfd

...to fix lxqt-panel auto-hiding which is currently broken when the panel size
is greater than 40 (height when panel is in horizontal mode). This is because
lxqt-panel has a `#define PANEL_HIDE_SIZE 4` which means it is ignored by the
compositor because of `if (overlap >= 0.1 * visible_area) { ...` in
`update_node_update_outputs()` in `wlr_scene.c`.

Have tested this patch on the wlroots-0.20 branch with labwc-0.20.0 and confirm
it fixes the auto-hiding issue.

Ref:
- https://github.com/labwc/labwc/issues/3600
- 95b2771bfd
- 78e5e279cc/panel/lxqtpanellimits.h (L34)

Note: `git revert 95b2771` resulted in many conflicts, so this patch includes
significant manual editing.

types/scene/wlr_scene.c

@@ -417,8 +417,6 @@ static void update_node_update_outputs(struct wlr_scene_node *node,
 	uint64_t active_outputs = 0;
 
 	if (!pixman_region32_empty(&node->visible)) {
-		uint32_t visible_area = region_area(&node->visible);
-
 		// let's update the outputs in two steps:
 		//  - the primary outputs
 		//  - the enter/leave signals
@@ -449,9 +447,6 @@ static void update_node_update_outputs(struct wlr_scene_node *node,
 			uint32_t overlap = region_area(&intersection);
 			pixman_region32_fini(&intersection);
 
-			// If the overlap accounts for less than 10% of the visible node area,
-			// ignore this output
-			if (overlap >= 0.1 * visible_area) {
 			if (overlap >= largest_overlap) {
 				largest_overlap = overlap;
 				scene_buffer->primary_output = scene_output;
@@ -461,7 +456,6 @@ static void update_node_update_outputs(struct wlr_scene_node *node,
 			count++;
 		}
 	}
-	}
 
 	// if there are active outputs on this node, we should always have a primary
 	// output