Remove auto-generation of db schema from models at startup

This patch removes the Neutron capability of creating database tables
from sqlalchemy models for all those model classes for which
a table is not found in the database schema.
Migrations should be the official and only solution for creating and
managing the Neutron db schema.
This patch also adapts unit tests in order to ensure test schemas
are still correctly created.

DocImpact
Update deployment documentation accordingly.

Closes-Bug: #1207402

Change-Id: Ie4ee5507888ecad5f6dc32ce7a029c43014687a2
Co-Authored-By: Henry Gessau <gessau@cisco.com>

neutron/db/vpn/vpn_db.py

@@ -21,7 +21,6 @@ from sqlalchemy import orm
 from sqlalchemy.orm import exc
 
 from neutron.common import constants as n_constants
-from neutron.db import api as qdbapi
 from neutron.db import common_db_mixin as base_db
 from neutron.db import l3_agentschedulers_db as l3_agent_db
 from neutron.db import l3_db
@@ -162,10 +161,6 @@ class VPNService(model_base.BASEV2, models_v2.HasId, models_v2.HasTenant):
 class VPNPluginDb(vpnaas.VPNPluginBase, base_db.CommonDbMixin):
     """VPN plugin database class using SQLAlchemy models."""
 
-    def __init__(self):
-        """Do the initialization for the vpn service plugin here."""
-        qdbapi.register_models()
-
     def _get_validator(self):
         """Obtain validator to use for attribute validation.
 

neutron/tests/unit/services/vpn/service_drivers/test_cisco_ipsec.py

@@ -16,7 +16,6 @@ import mock
 # from oslo.config import cfg
 
 from neutron import context as n_ctx
-from neutron.db import api as dbapi
 from neutron.openstack.common import uuidutils
 from neutron.plugins.common import constants
 # from neutron.services.vpn import plugin as vpn_plugin
@@ -24,6 +23,7 @@ from neutron.services.vpn.service_drivers import cisco_csr_db as csr_db
 from neutron.services.vpn.service_drivers import cisco_ipsec as ipsec_driver
 from neutron.services.vpn.service_drivers import cisco_validator as validator
 from neutron.tests import base
+from neutron.tests.unit import testlib_api
 
 _uuid = uuidutils.generate_uuid
 
@@ -328,14 +328,12 @@ class TestCiscoIPsecDriverMapping(base.BaseTestCase):
                                             tenant_id='1000')
 
 
-class TestCiscoIPsecDriver(base.BaseTestCase):
+class TestCiscoIPsecDriver(testlib_api.SqlTestCase):
 
     """Test that various incoming requests are sent to device driver."""
 
     def setUp(self):
         super(TestCiscoIPsecDriver, self).setUp()
-        dbapi.configure_db()
-        self.addCleanup(dbapi.clear_db)
         mock.patch('neutron.common.rpc.create_connection').start()
 
         l3_agent = mock.Mock()