Revert "use default OID if missing in model"

discussed with Guillaum on IRC. This changes is to invasif for a
stable release.

This reverts commit dd327fcbc95ebc58a78d56760c7b1d3e016283f3.
Merge branch '2.3.x' of git+ssh://forge.fusioninventory.org/git/fusioninventory/agent into 2.3.x
Merge remote-tracking branch 'origin/2.3.x' into 2.3.x