Fix PHP 8.3 "Usage of ldap_connect with two arguments is deprecated" exception

Summary:
Per https://www.php.net/manual/en/function.ldap-connect.php the signature $conn = @ldap_connect($host, $this->port); is deprecated since PHP 8.3.
Thus pass a full LDAP URI as the only parameter.

ERROR 8192: Usage of ldap_connect with two arguments is deprecated at [/var/www/html/phorge/phorge/src/applications/auth/adapter/PhutilLDAPAuthAdapter.php:308]

Closes T15724

Test Plan: Set up LDAP as auth provider, try to log in.

Reviewers: O1 Blessed Committers, avivey

Reviewed By: O1 Blessed Committers, avivey

Subscribers: avivey, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T15724

Differential Revision: https://we.phorge.it/D25792