Pregenerate the database schema we should use for most tests.
Currently, Cockroach is slow with regards to migration and it's
better if it happens in as few transactions as possible.
This reduces test time from ~21min to ~15min.
Change-Id: Ife8117053e6b9ecf3c93fe63677edf15d4d7c254
Now that the deprecated downtime tracking service is removed
(3fc76f4ffe), we can safely remove
the nodes_offline_times table.
Change-Id: Ia7c6efe32ba104dff5a830af5f2beee3337eefe5