Fix type of uniq_security_groups0project_id0name0deleted

Migration 190 created uniq_security_groups0project_id0name0deleted but
added it to the model as an index instead of a UniqueConstraint.

Change-Id: Id01c2207a6d2b59cc0f9c4301d696d8a3dd82df7
Partially-implements: blueprint validate-migrations-and-model
Merge "Fix type of uniq_security_groups0project_id0name0deleted"