[REST] PfcpAssocState: field 'lrts' is required
The local RTS is always known and thus always gets included regardless
of the PFCP association state. Only the remote RTS is optional.
Change-Id: Ic766ebc56ce1810fc27cb49ddcac50bc94e539d9
Related: osmo-ttcn3-hacks.git I332e95a32935e0c8da99e600e8d30af14bd36b16
