MAINT faster test_weight_boosting
TST speedup test_spectral_biclustering
TST faster check_transformer_pickle by fixing n_iter
TST speedup test_permutation_score

Also remove a warning with fbeta score that had non enought samples of
a specific class by chance.
TST remove joblib tests from sklearn
Merge pull request #3403 from ogrisel/speedup-tests

[MRG] Make tests faster to run