Remove unused cloud builder configs & packer jobs

Since these are not being used anywhere in ci-management, they no
longer need to be maintained. This will simplify maintenance, and the
builders can always be re-added if they become necessary again.

Change-Id: I04a0dffc2672eb84958b6279081b858d4f2f8cf5
Signed-off-by: Eric Ball <eball@linuxfoundation.org>