install: ldap conn management
* Move connect to the beggining of the uninstall_check and properly
close the connection at the end of the script.
* Connect to ldap in external CA installation (step2).
https://fedorahosted.org/freeipa/ticket/6461
Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Jan Cholasta <jcholast@redhat.com>