Murano migrations failed due to mysql driver was updated in devstack

[Ekaterina Chernova]

After fix https://github.com/openstack-dev/devstack/commit/1e6b33377f4f6dd82a65070da0ac811fae3bd905 in devstack,
murano migrations failed

Need to adopt this in murano

[Ekaterina Chernova (efedorova)]

The problem is more complicated, that we expected

We do support SQLite migrations. that why we do have this function to support 'alter' in sqlite:

https://github.com/openstack/murano/blob/master/murano/db/migration/alembic_migrations/versions/004_change_package_desc_type.py#L39

After switching to pymysql, force ignoring of foreign keys in Mysql is not working, so it's not possible to drop the table in transform_table functions.

We can drop sqlite support and use alter in this migration.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/190870

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/190870
Committed: https://git.openstack.org/cgit/openstack/murano/commit/?id=508739984da3740d8d2fe1acb84ebce88688c7f1
Submitter: Jenkins
Branch: master

commit 508739984da3740d8d2fe1acb84ebce88688c7f1
Author: Kirill Zaitsev <email address hidden>
Date: Fri Jun 12 02:51:16 2015 +0300

    Migrations: ignore mysql fk cheks for any mysql driver

    Before mysql migrations disabled foreign key checks only for
    mysql+mysqldb engine. Currently mysql+pymysql is preferred engine. This
    change disables FK checks for any mysql engine available.

    Change-Id: I536480559260c4be11b6e615c0df8f012798be9d
    Closes-Bug: #1464271