Administration: Use wp_admin_notice() in wp-admin/network/.

Add additional usage of `wp_admin_notice()` in `wp-admin/network/` where previously overlooked. 

Follow up to [56408], [56409], [56410], [56518], [56570], [56571], [56572], [56573], [56576], [56589], [56590], [56597], [56599], [56600].

Props costdev, joedolson.
See #57791.

git-svn-id: https://develop.svn.wordpress.org/trunk@56601 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/network/themes.php

@@ -135,11 +135,25 @@
 				<div class="wrap">
 				<?php if ( 1 === $themes_to_delete ) : ?>
 					<h1><?php _e( 'Delete Theme' ); ?></h1>
-					<div class="error"><p><strong><?php _e( 'Caution:' ); ?></strong> <?php _e( 'This theme may be active on other sites in the network.' ); ?></p></div>
+					<?php
+					wp_admin_notice(
+						'<strong>' . __( 'Caution:' ) . '</strong> ' . __( 'This theme may be active on other sites in the network.' ),
+						array(
+							'additional_classes' => array( 'error' ),
+						)
+					);
+					?>
 					<p><?php _e( 'You are about to remove the following theme:' ); ?></p>
 				<?php else : ?>
 					<h1><?php _e( 'Delete Themes' ); ?></h1>
-					<div class="error"><p><strong><?php _e( 'Caution:' ); ?></strong> <?php _e( 'These themes may be active on other sites in the network.' ); ?></p></div>
+					<?php
+					wp_admin_notice(
+						'<strong>' . __( 'Caution:' ) . '</strong> ' . __( 'These themes may be active on other sites in the network.' ),
+						array(
+							'additional_classes' => array( 'error' ),
+						)
+					);
+					?>
 					<p><?php _e( 'You are about to remove the following themes:' ); ?></p>
 				<?php endif; ?>
 					<ul class="ul-disc">