Revert "Add index on trunk_id in the subports model"

It was pointed out after merge that the index is, in fact, redundant.

This reverts commit 6d8d00fea1.

Change-Id: I1dad14079d01f5441005be8fa0b3de8d3d06429c

neutron/db/migration/alembic_migrations/versions/EXPAND_HEAD

@@ -1 +1 @@
-0e877ec3cba3
+30107ab6a3ee

neutron/db/migration/alembic_migrations/versions/newton/expand/0e877ec3cba3_add_index_to_trunk_model_and_adjust_.py

@@ -1,25 +0,0 @@
-#    Licensed under the Apache License, Version 2.0 (the "License"); you may
-#    not use this file except in compliance with the License. You may obtain
-#    a copy of the License at
-#
-#         http://www.apache.org/licenses/LICENSE-2.0
-#
-#    Unless required by applicable law or agreed to in writing, software
-#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-#    License for the specific language governing permissions and limitations
-#    under the License.
-
-"""Add index on trunk_id to subports model """
-
-revision = '0e877ec3cba3'
-down_revision = '30107ab6a3ee'
-
-from alembic import op
-
-
-def upgrade():
-    op.create_index('ix_subports_trunk_id',
-                    'subports',
-                    ['trunk_id'],
-                    unique=False)

neutron/services/trunk/models.py

@@ -56,7 +56,6 @@ class SubPort(model_base.BASEV2):
     segmentation_id = sa.Column(sa.Integer, nullable=False)
 
     __table_args__ = (
-        sa.Index('ix_subports_trunk_id', 'trunk_id'),
         sa.UniqueConstraint(
             'trunk_id',
             'segmentation_type',