Fix oauth2 builtin application logic (#30304) (#30327)

Backport #30304 by wxiaoguang

Fix #29074 (allow to disable all builtin apps) and don't make the doctor
command remove the builtin apps.

By the way, rename refobject and joincond to camel case.

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/doctor/main_test.go

@@ -0,0 +1,14 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package doctor
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/unittest"
+)
+
+func TestMain(m *testing.M) {
+	unittest.MainTest(m)
+}