Do not list disabled user accounts in mail footer (when metamta.recipients.show-hints is enabled) and do not add them to the X-Phabricator-Cc header, as they are not supposed to receive mail anyway per https://we.phorge.it/source/phorge/browse/master/src/applications/metamta/query/PhabricatorMetaMTAActor.php;07723b46274c6dbf062af070e5c19101537e0d91$130-131.

Closes T16033

Likely trigger notifications on a task or changeset with disabled user accounts being subscribed or members/watchers of a project. Not tested though as I do not have a local mail setup.