Remove obsolete add-ons during openHAB 3 upgrade

[stefan-oh]

As discussed in Installing and testing OH3 some ui configurations are obsolet with OH3. At least the entry "paper" in the configuration file /var/lib/openhab/config/org/openhab/addons.config needs to be deleted from every configuration that was taken over from a previous OH2 installation.
As other configuration files in the same folder are amended, my suggestion would be to delete the ui entries that are obsolete with OH3. As far as I know at least
paper
classic
dashboard
habmin

fall into that category (there might be more).

Some of these obsolete entries might be avoidable by uninstalling the respective addons BEFORE the migration, but afterwards it cannot be cleared up via GUI as only valid addons are shown in the GUI. Cleaning up by editing the file might not be something every user feels comfortable to do.

[kaikreuzer]

Good point.
@BClark09 Do you see any chance to do that through some sed magic within the update script?

[wborn]

When #1481 gets fixed we might be able to backport it to OH3.