If 'RECREATE_KEYSTONE_DB=False' database won't be recreated.
It would be useful for multinode Grenade tests for Keystone. This parameter
will help us to deploy multiple services on different machines talking to
the same DB.
Devstack recreates Keystone DB each time during Keystone service installation.
If our controller node is already deployed, Keystone DB already contains
important information about OpenStack services and their endpoints. When
the second Keystone node is being deployed, we don't want to delete
records about controllers' services endpoints.
Partially-Implements: bp rolling-upgrade-testing
Change-Id: Ia8d07b4295ca165be01e44466c95d5275f596e83
ea3e87d4e5