Move test_insert_from_select unit test from nova to oslo

Nova had it's own copy of InsertFromSelect so change Iefa5b431 is
removing that copy from Nova to use the version in Oslo. The only
difference is Nova had an additional unit test for InsertFromSelect so
we can move that to Oslo.

Partial-Bug: #1280055

Change-Id: I457acf335c4877c398c443b0cfde55bb997dfe6d
Merge "Move test_insert_from_select unit test from nova to oslo"