All the list model tests were leaking items,
because g_list_model_get_item is transfer full.
Fixing these unveils a crash in the treelistmodel
and maplistmodel tests.
The calls used old bugzilla URLs and nobody cared about that.
So apparently they are very unused.
There's also a potential conflict between gitlab and bugzilla URLs and
what base bug to use there.
The old usages have been converted to comments.
