Remove disco support from the charm

Change-Id: I551869cc8b4bd0a68c8152d3fc24b1e1404583b9

src/metadata.yaml

@@ -14,7 +14,6 @@ tags:
 series:
   - xenial
   - bionic
-  - disco
   - eoan
   - trusty
 subordinate: false

src/tests/bundles/disco_stein.yaml

@@ -1,72 +0,0 @@
-series: disco
-
-machines:
-  '0':
-    constraints: mem=3072M
-  '1':
-  '2':
-  '3':
-  '4':
-  '5':
-  '6':
-
-applications:
-  neutron-api:
-    charm: cs:~openstack-charmers-next/neutron-api
-    num_units: 1
-    to:
-    - '6'
-  percona-cluster:
-    charm: cs:~openstack-charmers-next/percona-cluster
-    num_units: 1
-    to:
-    - '0'
-  keystone:
-    charm: cs:~openstack-charmers-next/keystone
-    num_units: 1
-    to:
-    - '1'
-  rabbitmq-server:
-    charm: cs:~openstack-charmers-next/rabbitmq-server
-    num_units: 1
-    to:
-    - '2'
-  designate-bind:
-    charm: cs:~openstack-charmers-next/designate-bind
-    num_units: 1
-    to:
-    - '3'
-  memcached:
-    charm: cs:~memcached-team/memcached
-    num_units: 1
-    to:
-    - '4'
-  designate:
-    charm: ../../../designate
-    num_units: 1
-    options:
-      nameservers: 'ns1.amuletexample.com. ns2.amuletexample.com.'
-    to:
-    - '5'
-
-relations:
-- - 'designate:shared-db'
-  - 'percona-cluster:shared-db'
-- - 'designate:amqp'
-  - 'rabbitmq-server:amqp'
-- - 'designate:identity-service'
-  - 'keystone:identity-service'
-- - 'keystone:shared-db'
-  - 'percona-cluster:shared-db'
-- - 'designate:dns-backend'
-  - 'designate-bind:dns-backend'
-- - 'designate:coordinator-memcached'
-  - 'memcached:cache'
-- - 'designate:dnsaas'
-  - 'neutron-api:external-dns'
-- - 'neutron-api:identity-service'
-  - 'keystone:identity-service'
-- - 'neutron-api:shared-db'
-  - 'percona-cluster:shared-db'
-- - 'neutron-api:amqp'
-  - 'rabbitmq-server:amqp'