plot_identification.m: fix placing of white dots

9 jobs for plot_identification in 14 minutes and 41 seconds (queued for 4 minutes and 40 seconds)
Status Job ID Name Coverage
  Build
passed #9488
build_binaries

00:10:54

passed #9489
build_doc

00:01:14

 
  Test And Pkg
canceled #9492
macOS
pkg_macOS

00:03:47

passed #9490
pkg_source

00:02:04

canceled #9491
pkg_windows

00:01:42

canceled #9496
test_dynare++

canceled #9493
test_matlab

manual #9495
allowed to fail manual
test_octave
manual #9494
allowed to fail manual
test_old_matlab