Do not return any contact lists in GAL searches:

Rationale is that the protocol only defines the GAL::Email field
as containing a single email address, and most, if not all, clients
assume this, and do some munging of this value along with Alias and
Name to get the actual To header to send. Even using the group
syntax (group_name : user@example.com, otheruser@example.com;) causes
most clients to choke. This leads, in the best case to notifying the
user that the email can't be sent or, the worst case, silently discarding
all email addresses except one from the group and sending the email anyway.
Fix sending an empty 'entries' array in ResolveRecipients responses.
This value is only used for Exchange Distribution Lists (which we don't support).