Fix unlabeled Remove shadow buttons. (WordPress#63197)

Replace tooltip and ariaLabel with label to ensure that the "Remove shadow" button is labeled.

Co-authored-by: afercia <afercia@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>
Co-authored-by: carolinan <poena@git.wordpress.org>
Co-authored-by: mirka <0mirka00@git.wordpress.org>

packages/edit-site/src/components/global-styles/shadows-edit-panel.js

@@ -371,8 +371,7 @@ function ShadowItem( { shadow, onChange, canRemove, onRemove } ) {
 						'edit-site-global-styles__shadow-editor__remove-button',
 						{ 'is-open': isOpen }
 					),
-					ariaLabel: __( 'Remove shadow' ),
-					tooltip: __( 'Remove shadow' ),
+					label: __( 'Remove shadow' ),
 				};
 
 				return (