ANDROID: gki/cuttlefish defconfigs: use prebuilt build-tools

Rather than relying on the hosts build tools, use a set of prebuilt
build-tools. These are tools like awk, cat, cp, hostname, python, rm,
sed, etc.

Bug: 135922132
Change-Id: Ie6b0bd208c684c9f153eb2f0bfac4712e02e8e05
Signed-off-by: Matthias Maennich <maennich@google.com>