Test missing in lists_lists leading to wrong listing when using -V option

Dear project leader,

When we list the lists for specific virtualhost, a wrong result can be printed-out in the following condition:

Let's say we have somme lists hosted on bbox.nuxwin.com virtualhost and other lists on the lists.bbox.nuxwin.com virtualhost. Then, when running list_lists as follow:

list_lists -b -V bbox.nuxwin.com

We get also the lists names from the lists.bbox.nuxwin.com virtualhost which is an unexpected behavior.

This is due to the fact that you're using find() only.

Real use case:

# Expected result:
root@devuan:~# /usr/lib/mailman/bin/list_lists -b -V lists.bbox.nuxwin.com
foo
bar

# Unexpected result:
root@devuan:~# /usr/lib/mailman/bin/list_lists -b -V bbox.nuxwin.com
foo
bar

# Unexpected result:
root@devuan:~# /usr/lib/mailman/bin/list_lists -b -V nuxwin.com
foo
bar

# Unexpected result:
root@devuan:~# /usr/lib/mailman/bin/list_lists -b -V com
foo
bar

# Unexpected result:
root@devuan:~# /usr/lib/mailman/bin/list_lists -b -V m
foo
bar

Thank you.