build: cross compile darwin builds

[dhiaayachi]

Description

For cost reasons, we can cross-compile macos binaries on linux. Historically we didn't do this because of a problem with Go that has since been resolved: hashicorp#3267.

This step removes the verification of Darwin binaries. I believe this is acceptable since the vast majority of users and on Linux and Windows. Developers will naturally test the Darwin build during the development cycle.