I think you don’t need to edit the /etc/postfix/ldap-domains.cf anymore. That setting, it seems, is now changed through disabling the mail_in setting of the domain, which now changes the managed file /etc/postfix/virtual-mailbox-domains.
However, there seem to be remaining issues, e.g. the local MX override is bound to mail_in enabled/disabled instead of DNS diagnosis results, and thus even removed if the public SPF etc. for sending is not set up properly yet (risk to get own IP blacklisted e.g. by status/notification emails), and further bugs/issues can also still be experienced in email transport/delivery/reception after disabling mail_in/out settings, see: Issues to fix email breakages caused by upgrades (regression) - #3 by tmb