All code paths which eventually call GroupNameNotes#loadAllGroups don't
care whether groups with duplicated UUIDs are cleaned up in the list of
all groups or not. They are robust enough to work either way.
There are both arguments for cleaning them up and not doing so. As not
cleaning them up might be a bit more robust in the long term and also
helps to concentrate the logic regarding how to read the notes written
by GroupNameNotes more within GroupNameNotes, we now hand out all known
groups irrespective of their UUID.
Change-Id: Idd8e6d4420ad254a378388fdd66eedae0a51ffed
cbae08edf8