Update add_non_persistent_groups()

Don't allow groups that were manually removed using `WP_REDIS_IGNORED_GROUPS` constant to be added to the ignored groups list.

* FIxes rhubarbgroup#114
* Fixes rhubarbgroup#74
* Ref: https://core.trac.wordpress.org/ticket/47884#ticket

includes/object-cache.php

@@ -2417,7 +2417,21 @@ public function add_global_groups( $groups ) {
      * @param array $groups  List of groups that are to be ignored.
      */
     public function add_non_persistent_groups( $groups ) {
-        $groups = (array) $groups;
+        $groups          = (array) $groups;
+        $default_groups  = [ 'counts', 'plugins', 'themes' ];
+
+        static $groups_override        = null;
+        static $removed_default_groups = null;
+
+        if ( is_null( $groups_override ) && defined( 'WP_REDIS_IGNORED_GROUPS' ) && is_array( WP_REDIS_IGNORED_GROUPS ) ) {
+            $groups_override        = array_map( [ $this, 'sanitize_key_part' ], WP_REDIS_IGNORED_GROUPS );
+            $removed_default_groups = array_diff( $default_groups, $groups_override );
+        }
+
+        if ( $removed_default_groups && array_intersect( $groups, $removed_default_groups ) ) {
+            // Don't allow default groups that were manually removed via WP_REDIS_IGNORED_GROUPS constant to be readded.
+            return;
+        }
 
         $this->ignored_groups = array_unique( array_merge( $this->ignored_groups, $groups ) );
     }