With Go modules, `go mod tidy` supplants `vendorfmt`. Unfortunately,
`tidy` will try to reach out to the network and download modules, and
there is no way to disable that behavior (e.g. the -mod=vendor) option
does not apply. This means we cannot use the `tidy` target in nomad
enterprise, which will be unable to reach private repositories like
consul-enterprise.

This isn't a big deal, since `vendorfmt` served the purpose of rewriting
the output of `govendor`, wheras `tidy` is a part of the `sync` target
that is required to be run when modifying dependencies anyway.