Add and check data functions for test_migrations 141

Before the 141 migration test is run, _prerun_141 populates the migrations
table with a generated uuid. The _check_141 function checks that
the uuid migrated properly down to 36 char.

Partially implements: blueprint migration-testing-with-data

Change-Id: I43b47f69a94720bf9487eb30576035493700ddca
Merge "Add and check data functions for test_migrations 141"