Drop the mailman_copy Exim router

In Ic1156849957bc326e9216c2aca0ab9d180e158e6 we added a temporary
router named mailman_copy to dump raw messages for the
openstack-discuss mailing list to an mbox file at
/var/mail/openstack-discuss in order to be able to compare
pre-Mailman state of messages for DKIM signature debugging. Since
this file doesn't exist and Exim lacks permission to create it, the
resulting router errors are leading to message deferrals for the
openstack-discuss mailing list.

Rather than add Ansible to create the mbox file for this, just drop
the router and accompanying transport definitions from our Exim
config. We can always set it up more thoroughly in the future if we
ever want to re-add it.

Change-Id: If4f6c7b90b7b312b23a7736251f704dace668879

inventory/service/group_vars/mailman3.yaml

@@ -48,12 +48,6 @@ exim_routers:
       file_transport = address_file
       pipe_transport = address_pipe
   - localuser: '{{ exim_localuser_router }}'
-  - mailman_copy: |
-      driver = accept
-      domains = lists.openstack.org
-      local_parts = openstack-discuss
-      transport = local_copy
-      unseen
   - mailman_router: |
       driver = accept
       domains = {{ mm_domains }}
@@ -67,11 +61,6 @@ exim_routers:
       require_files = /var/lib/mailman/core/var/lists/${local_part}.${domain}
       transport = mailman_transport
 exim_transports:
-  - local_copy: |
-      driver = appendfile
-      file = /var/mail/$local_part
-      group = mail
-      mode = 0660
   - mailman_transport: |
       debug_print = "Email for mailman"
       driver = smtp

playbooks/zuul/files/host_vars/lists99.opendev.org.yaml

@@ -82,12 +82,6 @@ exim_routers:
       file_transport = address_file
       pipe_transport = address_pipe
   - localuser: '{{ exim_localuser_router }}'
-  - mailman_copy: |
-      driver = accept
-      domains = lists.openstack.org
-      local_parts = openstack-discuss
-      transport = local_copy
-      unseen
   - mailman_router: |
       driver = accept
       domains = {{ mm_domains }}
@@ -101,11 +95,6 @@ exim_routers:
       require_files = /var/lib/mailman/core/var/lists/${local_part}.${domain}
       transport = mailman_transport
 exim_transports:
-  - local_copy: |
-      driver = appendfile
-      file = /var/mail/$local_part
-      group = mail
-      mode = 0660
   - mailman_transport: |
       debug_print = "Email for mailman"
       driver = smtp