Plugins: Remove pluginsCDNSyncLoader feature toggle (#108389)

* remove pluginsCDNSyncLoader feature toggle

* fix lint issues

* fix other linter issue

packages/grafana-data/src/types/featureToggles.gen.ts

@@ -847,10 +847,6 @@ export interface FeatureToggles {
   */
   grafanaconThemes?: boolean;
   /**
-  * Loads plugins from CDN synchronously
-  */
-  pluginsCDNSyncLoader?: boolean;
-  /**
   * Enables the new Jira integration for contact points in cloud alert managers.
   */
   alertingJiraIntegration?: boolean;