[tooling] Add automatic database migration tests

[the-glu]

Right now, there are no automatic database migrations test.

There is indirect testing via CI, because we do apply then, but we don't verify that they can be down and that they do a correct cleanup, leading to human verifications to ensure everything is ok.

This PR add automatic migration tests that check:

• That migrations can be applied
• That those migrations created table
• That migrations can be 'un-applied'
• That those down migrations removed all tables
• That we can re-apply migrations after that (just in case there are some leftovers)

This is not perfect (e.g. one can forgot to cover both datastore types), but should cover basic cases.

This also fix down migrations of yugabyte that where missing version set in two migration.