Plugins Catalog: Make the catalog the default way to interact with plugins (#39779) (#39822)

* chore(Plugins/Admin): make the Plugins Catalog the default way to interact with plugins

* chore(defaults.ini): change the default value for `plugin_admin_enabled`

* test(Plugins): make the tests pass

(cherry picked from commit c2754eb9cc)

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

packages/grafana-runtime/src/config.ts

@@ -79,7 +79,7 @@ export class GrafanaBootConfig implements GrafanaConfig {
     sampleRate: 1,
   };
   pluginCatalogURL = 'https://grafana.com/grafana/plugins/';
-  pluginAdminEnabled = false;
+  pluginAdminEnabled = true;
   pluginAdminExternalManageEnabled = false;
   expressionsEnabled = false;
   customTheme?: any;