I'm digging through the neon csit failures to help sign off for the
release, and came across a failure in neon csit that is not there in
fluorine.

We need to explain it or fix it so we can get the (now late) Neon
release done.

Essentially, the failure is that a GET to
/restconf/config/neutron:neutron/l2gatewayConnections
is coming back 404 after the last l2-gateway-connection is deleted
(done with the neutron CLI). So we get a 404 [1] and this:

"error-tag":"data-missing","error-message":"Request could not be completed
because the relevant data model content does not exist"


In Fluorine [2], we get a 200 and this:

    {"l2gatewayConnections":{}}


How do we want to handle it? I'll make a note on the tracking sheet [3]
and keep it as pending for now.