move retag and retag-lite to using MC20
Right now some systematics we'll want in retagging aren't supported in mc23. I'm moving tests over to using mc20 so that we can build tests around these systematics, as we're doing in !648 (merged).
Right now some systematics we'll want in retagging aren't supported in mc23. I'm moving tests over to using mc20 so that we can build tests around these systematics, as we're doing in !648 (merged).