According to the Horizon documentation for Settings and Configuration,
for a plugin panel, 'If you want the panel to show up without a panel
group, use the panel group “default”'. In some cases, plugin panels were
getting put under the panel group "Other" instead. This is because
the default panel group wasn't getting created during plugin panel
processing when the panel's dashboard class already had some panel
groups defined. Fix this by making sure a default panel group is created
in each dashboard.
Change-Id: I98064c434326aabec16b5d1631e360643609ed40
Closes-Bug: 1403094
c3864ab35c