Update via ./init.sh will now clone and update to defined and testet
yocto release.
A general update is disabled with variable $YOCTO_LAYER_DO_UPDATE=0
Reason: yocto recomends not to modify any parts of the yocto repositories. becaus all
Local changes can be done in your local layers e.g. with bbappend files.
see also: https://www.yoctoproject.org/docs/current/mega-manual/mega-manual.html#using-bbappend-files
Another point is, the defined relase version is tested and should working
with our build.