Change default qualifier on viewpoint generation

[pdulth]

The default qualifier used while generating a viewpoint intend that the viewpoint will be opensource and hosted by Eclipse Foundation, but its not generally the case (at least at first).
It shall be better to keep empty the qualifier or at least inform user that the qualifier used at creation implies that this addon has to be managed within Eclipse Foundation and have to be generally changed.

https://github.com/eclipse/capella-studio/blob/88b9a68f924f300665074b532d5c069287b291bc/vpdsl/plugins/org.polarsys.capella.ta/plugin.xml#L17