Added Postgres CI opportunistic test case

Added test case and support functions for CI opportunistic testing
using a PostgreSQL database, as part of our postgresql as a first
class citizen effort.

rebased again on top of test migration with data framework

clean up debug, and ensure pg will fail to connect gracefully

fix previous migration test which was inserting a key by id, which
postgresql doesn't like, as it doesn't adjust the autoincrement
counter.

added driver to connection string for mysql

Updated comment to expose how to do this on pg easily

Fixes:
bug 1084567

Change-Id: If0bfe5cf748f6d5724d17082be6d18b6f96f6ee4
Merge "Added Postgres CI opportunistic test case"