In order to support smoke-testing with a single server, the update
tests are refactored. This is part of a longer sequence of changes to
support both running smoke tests and update tests and contain the
following changes:
- All timestamp columns now have `not null` added to avoid spamming the
output file and help finding the real issue.
- Extension of dump files are changed from `sql` to `dump` since they
use the custom format and are not SQL files.