refactor: "install" page (#39400)

1. remove useless options
2. set AppDataPath instead of repo root path
3. make "disable self-registration" default enabled
4. avoid writing corrupted ini file
5. avoid auto-sign-in the existing admin user

tools/test-e2e.sh

@@ -109,6 +109,7 @@ INSTALL_LOCK = true
 
 [service]
 ENABLE_CAPTCHA = false
+DISABLE_REGISTRATION = false
 
 [ui.notification]
 EVENT_SOURCE_UPDATE_TIME = 500ms