[script][figure,test_script] Fix nbins for hist: only depends on the #histos in the figure

4 jobs for bins in 11 minutes and 9 seconds (queued for 6 seconds)
Status Job ID Name Coverage
  Build
passed #140522
docker
build_linux_27

00:11:05

86.0%
passed #140523
docker
build_linux_36

00:11:07

86.0%
passed #140524
macosx
build_macosx_27

00:08:49

86.0%
passed #140525
macosx
build_macosx_36

00:08:14

86.0%