Align build scripts to LF

Align build scripts to LF

 - In LF we shall build docker containers on every build. Improvement to
   this process would be to separate these two docker environments from the
   build-tools repo. They could publish images to LF Nexus3 from where
   build-tools could directly utilize then.

 - There is not need to download ISO image dependencies from the Nexus3
   thus this code is removed. Now they will be downloaded directly from the
   internet with wget.

Change-Id: I8cbc89a1c25a5dedc0ce0556d00e80c09995c976
Signed-off-by: Saku Chydenius <saku.chydenius@nokia.com>