Problem description: If Parameter "Bind password" in Administration => Authentication => LDAP settings is empty, it is possible to successfully test and to save LDAP authentication configuration without specifying mandatory parameter "Login".

Steps to reproduce:

1. Navigate to Administration => Authentication
2. Switch to "LDAP settings"
3. Fill in all mandatory fields with valid values except for field "Login". Make sure "Bind password" field is empty
4. Press test button
   Result 1: a message stating that the test was successful is returned
5. Attempt to update LDAP configuration
   Result 2: Configuration successfully updated

Expected: It should not be possible to test or update LDAP authentication cofiguration without specifying all mandatory parameters.

Example: