After a successful FCV 8.0 to FCV 9.0 upgrade all timeseries collections should be in viewless format. This is done using a combination of methods: setFCV draining, DDL coordinator, DDL lock, stop migrations, etc..

If there's a bug where a timeseries collection is not converted, it may not manifest as an issue since for example the read/write path does not check the FCV so it can successfully work with a viewful timeseries collection even in FCV 9.0.

Add a test hook to verify all collections are in viewless format after an upgrade to FCV 9.0.

The same considerations apply to downgrade.