MB-12802: Revert "Download 3rd-party deps by default"

This caused build breaks on some platforms

This reverts commit fbe6c2988ca8c6b3943237be2a07eca05c472274.

Change-Id: Ie9eb2483b627f02a32d0c7e90f18913fd2d34054
Reviewed-on: http://review.couchbase.org/43761
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>