Validate CREATE/DROP DATABASE functionality

[mcronce]

With the advent of vitessio/vitess#7989, this should work with vttestserver. We should either add an explicit test for it or add it to an existing framework test.

If Prisma is still using it in their default test harness, it probably makes the most sense to stop monkey patching that (or monkey patch it less, if anything else is still required) and allow that framework to validate the functionality.