Add fix for reservation index to icehouse

Cinder doesn't have backportable migrations, so ensure the index
is added every time the migration runs.

DB migration in master that does the same thing was made in the
following commits:
  4d56b91628518629b47997b93acd9cb1e48f87f5
  08b90190085a11bc99112472944c193672061e1f
  479d6050f3f07e12488e6bb9a40b0aec3452a19c

Change-Id: I8bdab1a70f0076312aba4d0b6c4417b335947680
Resolves-bug: #1348720
Merge "Add fix for reservation index to icehouse" into stable/icehouse