sync of local user deletes the local user

  Scenario: sync a local user
    Given user "local-user" has been created with default attributes in the database user backend
    When the administrator changes the display name of user "local-user" to "Test User" using the occ command
    And LDAP user "local-user" is resynced
    Then the command should have been successful
    And user "local-user" should not exist

This scenario added in PR #506 looks a bit surprising to me. The test does the command:

occ user:sync OCA\User_LDAP\User_Proxy -u local-user -m remove

local-user is in the local user database, not in LDAP. So of course it is not found in LDAP. The admin has specified -m remove so the command removes the user. But the user is (and always was) just in the local database, they never came from LDAP in the first place.

If I was the admin then I would be a bit surprised that the user:sync command could ever delete a "real local user", even when I use -m remove. I feel like I should get an error message whenever the UID specified after -u is a "real local user". I should not be able to accidentally mess up a "real local user" with the user:sync command. I should have to explicitly do a user:delete if I want to delete a "real local user" (e.g. before then doing user:sync to sync the same UID that has just been added to LDAP)

Start with the sync scenario added in PR #506 and the occ user:sync OCA\User_LDAP\User_Proxy -u local-user -m remove command described here. Trace how a local database user is handled when the UID is absent from LDAP, then define completion as preventing accidental deletion of that local user while preserving the intended explicit deletion workflow.