[fix/adaptedVariousStokesThresholds] Updated thresholds for tests
Updated thresholds for test_stokes, test_2cstokes2p2c, test_2cnistokes2p2cni and test_2cnistokes2p2cni_boundarylayer to make them pass.
Updated thresholds for test_stokes, test_2cstokes2p2c, test_2cnistokes2p2cni and test_2cnistokes2p2cni_boundarylayer to make them pass.