Editor package: fix block settings menu appearance (#9777)

Resolve the styling issue that were present in Gutenberg integrations
that rely on published npm packages. Outside of wp-admin context the
removed CSS line was causing the horizontal scrollbar to appear in
block settings menu.

packages/editor/src/components/block-settings-menu/style.scss

@@ -10,7 +10,6 @@
 	}
 
 	.editor-block-settings-menu__content {
-		width: 100%;
 		padding: $item-spacing - $border-width;
 	}