Download common-types files as part of regenerating samples

Ideally, we should not keep static copies of the common-types files. Instead, we should download them as part of test setup and in the setup for regenerating samples

Locate the test setup and the setup used for regenerating samples, then identify where the static common-types files are currently consumed. Make both setup paths download those files instead, and verify that tests and sample regeneration still complete successfully.

Written by the indexing model from the issue text.