Stop disting monolithic SDK for Mac SDK builds

The Mac SDK build is being reduced to just the build-tools and
platform-tools packages. I'm still working on refactoring those builds
not to require the monolithic SDK to be built first, but we can at least
stop distributing it (and other related files) now.

Most of these checks can likely go away once the build refactor is
complete, since we'll be able to move away from the `sdk` target to
something more specific. Right now there's a lot of logic around sdk
being in MAKECMDGOALS that I don't want to unravel with the current
build logic.

Bug: 187222815
Change-Id: I1f711ce063170e41078ad4a125bcd77340a1746c