fs2000_ns_common.inc: set order of approximation explicitly to 1

(cherry picked from commit 23cac089)

tests/kalman/lik_init/fs2000_ns_common.inc

@@ -120,5 +120,7 @@ end;
 
 data(file='../../fs2000/fsdat_simul.m');
 options_.diffuse_filter=1;
+options_.order=1;
+
 [dataset_, dataset_info, xparam1, hh, M_, options_, oo_, estim_params_, bayestopt_, bounds] = ...
     dynare_estimation_init(char(), M_.fname, [], M_, options_, oo_, estim_params_, bayestopt_);
\ No newline at end of file