plugins/flannel: organize test JSON alphabetically
plugins/flannel: organize test JSON alphabetically

Otherwise the test fails, since Go's JSON marshaller prints
dict items alphabetically in its String() call.

tangle329/cni,rosenhouse/cni,containernetworking/cni,tangle329/cni,containernetworking/plugins,mcastelino/cni,appc/cni,mcastelino/cni,squeed/plugins,containernetworking/plugins,appc/cni,rosenhouse/cni,squeed/plugins,containernetworking/cni,dcbw/cni,kad/cni,kad/cni,dcbw/cni