refactor: remove forum and topic feature chains

src/Admin/GlobalController.php

@@ -258,7 +258,7 @@ class GlobalController extends ControllerBase {
         if ($term_id > 0) {
             $term = get_term($term_id);
             $taxonomy = ($term && !is_wp_error($term)) ? (string) $term->taxonomy : 'category';
-            if (!in_array($taxonomy, ['category', 'topics'], true)) {
+            if ($taxonomy !== 'category') {
                 $taxonomy = 'category';
             }
             $args['tax_query'] = [[
@@ -350,28 +350,6 @@ class GlobalController extends ControllerBase {
             ];
         }
 
-        if (taxonomy_exists('topics')) {
-            $topics = get_terms([
-                'taxonomy'   => 'topics',
-                'hide_empty' => false,
-                'orderby'    => 'name',
-                'order'      => 'ASC',
-            ]);
-            if (!is_wp_error($topics)) {
-                foreach ($topics as $term) {
-                    $data[] = [
-                        'id'       => (int) $term->term_id,
-                        'term_id'  => (int) $term->term_id,
-                        'name'     => $term->name,
-                        'slug'     => $term->slug,
-                        'count'    => (int) $term->count,
-                        'parent'   => (int) $term->parent,
-                        'taxonomy' => 'topics',
-                    ];
-                }
-            }
-        }
-
         return $this->success(['data' => $data]);
     }