Use github org labels

[skjnldsv]

Github now provide default labels
https://github.com/organizations/nextcloud/settings/labels

Jan & I set them up, we should probable use those ones now instead of having two different settings that few people knows about :)
Unfortunately, the current org settings is only used for new repos, but there are tools available already https://github.com/dwyl/labels, https://github.com/Financial-Times/github-label-sync,

cc @rullzer @nickvergessen @MorrisJobke @jancborchardt

[nickvergessen]

Since it's only for new things, I would propose:

1. Create the labels which are in the defaults now in server, or decide it's not necessary and remove them from the defaults.
2. Run this tool so all repos in the list get the newly updated list.