Remove race condition (in InstanceTypes)

Soft delete all duplicate rows with the same name except one with
the biggest value in `id` column.

Soft delete all duplicate rows with the same flavorid except one with
the biggest value in `id` column.

Create UC on columns (name, deleted) and (flavorid, deleted)

Replace Select then Insert -> Try to Insert.

blueprint db-enforce-unique-keys

Change-Id: If66d2f1387c2b2748784bf7ac9746b8d755b70a9
Add missing tests for db.instance_type_access_* methods

There was no tests in test_db_api for instance_type_access_* methods.

Add tests to ensure that all works.
Also these tests allow us to refactor these methods.
For example add missing unique constraint on columns
(instance_type_id, project_id)

blueprint db-api-tests

Change-Id: Idfeda1685ef8c812c1211783aede15795b0d7caf
Merge "Remove race condition (in InstanceTypes)"
Merge "Add missing tests for db.instance_type_access_* methods"
Merge remote-tracking branch 'm_src_repo/master' into build-temp