user: remove make local feature

we discussed a bit on what this does and it's confusing as it stands:

* Use case of this is lost in the realms of time
* Possible guess by is that it was to move users of different Cloudron to a central cloudron
* Currently, the design is a bit flawed because the make user local button doesn’t pin the user. The state is lost in next synchronization.
* Maybe, one should use export/import user for this use case
* Let’s disable this button for now, feature is not complete.

src/server.js

@@ -191,7 +191,6 @@ async function initializeExpressSync() {
     router.post('/api/v1/users/:userId/password',      json, token, authorizeUserManager, routes.users.load, routes.users.setPassword);
     router.post('/api/v1/users/:userId/ghost',         json, token, authorizeAdmin,       routes.users.load, routes.users.setGhost);
     router.put ('/api/v1/users/:userId/groups',        json, token, authorizeUserManager, routes.users.load, routes.users.setGroups);
-    router.post('/api/v1/users/:userId/make_local',    json, token, authorizeUserManager, routes.users.load, routes.users.makeLocal);
     router.get ('/api/v1/users/:userId/password_reset_link',       json, token, authorizeUserManager, routes.users.load, routes.users.getPasswordResetLink);
     router.post('/api/v1/users/:userId/send_password_reset_email', json, token, authorizeUserManager, routes.users.load, routes.users.sendPasswordResetEmail);
     router.get ('/api/v1/users/:userId/invite_link',               json, token, authorizeUserManager, routes.users.load, routes.users.getInviteLink);