Janitorial: use wp_admin_notice function introduced in WP 6.4 (#37051)

* Janitorial: use wp_admin_notice function introduced in WP 6.4

Epic: #33615

* Handle possibility of no message

* Switch from string to array

* Add missing escaping

* Fix indenting

* Add missing escaping

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/8833248507

Upstream-Ref: Automattic/jetpack@993a91b

CHANGELOG.md

@@ -11,6 +11,7 @@ This is an alpha version! The changes listed here are not final.
 
 ### Changed
 - General: update WordPress version requirements to WordPress 6.4.
+- General: use wp_admin_notice function introduced in WP 6.4 to display notices.
 - Updated package dependencies.
 
 ### Fixed

partials/preload.php

@@ -4,7 +4,12 @@
 
 echo '<a name="preload"></a>';
 if ( ! $cache_enabled || ! $super_cache_enabled || true === defined( 'DISABLESUPERCACHEPRELOADING' ) ) {
-	echo '<div class="notice notice-warning"><p>' . __( 'Preloading of cache disabled. Please make sure simple or expert mode is enabled or talk to your host administrator.', 'wp-super-cache' ) . '</p></div>';
+	wp_admin_notice(
+		esc_html__( 'Preloading of cache disabled. Please make sure simple or expert mode is enabled or talk to your host administrator.', 'wp-super-cache' ),
+		array(
+			'type' => 'warning',
+		)
+	);
 	return;
 }