In order to update the tests from gen2 to gen3 in obs_decam, the repo in testdata_decam needs to be migrated to gen3.

John Parejko suggests starting with the scripts in testdata_jointcal that were used to convert the cfht repo from gen2 to gen3 as these were written more recently than the hsc repo there.

This ticket should also produce a butler export file so that tests in obs_decam can do a simple butler import to access the data.