Remove block_mouse_down in favor of stop_mouse_events_except_scroll (#30401)

This method was added in #20649 to be an alternative of `occlude` which
allows scroll events. It seems a bit arbitrary to only stop left mouse
downs, so this seems like it's probably an improvement.

Release Notes:

- N/A

crates/extensions_ui/src/components/extension_card.rs

@@ -48,7 +48,7 @@ impl RenderOnce for ExtensionCard {
                             .absolute()
                             .top_0()
                             .left_0()
-                            .block_mouse_down()
+                            .block_mouse_except_scroll()
                             .cursor_default()
                             .size_full()
                             .items_center()