Fixed errcheck issues in server/channels/app/plugin_hooks_test.go (#29059)

server/.golangci.yml

@@ -136,7 +136,6 @@ issues:
         channels/app/plugin_api_tests/test_update_user_auth_plugin/main.go|\
         channels/app/plugin_deadlock_test.go|\
         channels/app/plugin_health_check_test.go|\
-        channels/app/plugin_hooks_test.go|\
         channels/app/plugin_install.go|\
         channels/app/plugin_requests.go|\
         channels/app/plugin_signature.go|\