Drop unused dump_ SQL tables.

Drop the following tables which are no longer
used in Icehouse:
 -dump_compute_node_stats
 -dump_compute_nodes
 -dump_instance_actions
 -dump_instance_actions_events
 -dump_instance_faults
 -dump_migrations

Includes a new test to ensure the tables are dropped.

Change-Id: Ifa70b8dedebd074353560ac46d42a9cc5d133be2
Closes-bug: 1266538
Merge "Drop unused dump_ SQL tables."