Coding Standards: Remove unused local variable $all_class_directives.

This removes an unused variable in `WP_Interactivity_API::data_wp_class_processor()`.

Follow-up to [57563], [61020].

Props Soean.
See #64897.

git-svn-id: https://develop.svn.wordpress.org/trunk@62499 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-includes/interactivity-api/class-wp-interactivity-api.php

@@ -1086,8 +1086,7 @@ private function data_wp_bind_processor( WP_Interactivity_API_Directives_Process
 	 */
 	private function data_wp_class_processor( WP_Interactivity_API_Directives_Processor $p, string $mode ) {
 		if ( 'enter' === $mode ) {
-			$all_class_directives = $p->get_attribute_names_with_prefix( 'data-wp-class--' );
-			$entries              = $this->get_directive_entries( $p, 'class' );
+			$entries = $this->get_directive_entries( $p, 'class' );
 			foreach ( $entries as $entry ) {
 				if ( empty( $entry['suffix'] ) ) {
 					continue;