ldap: limit the retro changelog to dns subtree
The content synchronization plugin can be limited to the dns subtree in
Directory Server. This increases performance and helps to prevent some
potential issues.
Fixes: https://pagure.io/freeipa/issue/6515
Signed-off-by: Tomas Krizek <tkrizek@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>