[PA-A] cleanup scripts.

BayesValidRox/tests/PA-A/Benchmark_PAA.py

BayesValidRox/tests/PA-A/ffpm_validation_stokesdarcy.py

BayesValidRox/tests/PA-A/ffpm_validation_stokespnm.py

BayesValidRox/tests/PA-A/model_exe.py

...ox/tests/PA-A/models/stokespnm/ffpm_stokespnm_p_final.csv

...s/PA-A/models/stokespnm/ffpm_stokespnm_velocity_final.csv

...lidRox/tests/PA-A/models/stokespnm/model_stokespnm_exe.py

BayesValidRox/tests/PA-A/ref_stokespnm.py

BayesValidRox/tests/PA-A/util/vel_diagnostics.py