Improve performance of diskimage-builder based instances

    removed a ton of packages that are included in cloudimg
    removed reference to base element, it included extra kernel
    copied disabling of apt-recommends from base element
    add flag to diskimage-builder to skip base element

Fixes: bug/1118792

Change-Id: I03efaffa41689378d75646d227679dfb1a7082bc
Merge "Improve performance of diskimage-builder based instances"