…LLOWS UNAUTHENTICATED CONNECTIONS

Windows AD allows LDAP authentication with empty password.
After this fix AUTHENTICATION_LDAP_SIMPLE plugin will not try to perform LDAP bind when empty password is given.
Authentication will be considered as failed.

rb: 21910
Approved by: Georgi Kodinov <georgi.kodinov@oracle.com>
Approved by: Harin Vadodaria <harin.vadodaria@oracle.com>
Change-Id: Ie74d6b89f84670d5cd8a12f32fbe0030b91af3ea