Remove unnecessary checks from migration commands
Remove unnecessary checks from migration commands

When doing the alembic setup to enable the usage of the commands API,
there were some unnecessary checks in each command to verify that the
alembic configuration isn't a falsey value. Although, there is no
scenario where this could happen, since proper exceptions are thrown.
So this fixes that.

Change-Id: Ibc1b2ebefd13d7569e1ff69de873cfc557804a76

jmvrbanac/barbican,cneill/barbican,openstack/barbican,jmvrbanac/barbican,MCDong/barbican,cneill/barbican,MCDong/barbican,cloudkeep/barbican,cloudkeep/barbican,openstack/barbican