[T/RM] Use porosity from mass balance model.

Tests/Data/RichardsMechanics/LiakopoulosHM/liakopoulos.prj

Tests/Data/RichardsMechanics/RichardsFlow_2d_quasinewton.prj

Tests/Data/RichardsMechanics/RichardsFlow_2d_small.prj

...a/RichardsMechanics/RichardsFlow_2d_small_masslumping.prj

...ardsMechanics/alternative_mass_balance_anzInterval_10.prj

.../RichardsMechanics/bishops_effective_stress_power_law.prj

...sMechanics/bishops_effective_stress_saturation_cutoff.prj

...ichardsMechanics/confined_compression_fully_saturated.prj

...echanics/confined_compression_fully_saturated_restart.prj

...ardsMechanics/deformation_dependent_porosity_swelling.prj

Tests/Data/RichardsMechanics/flow_fully_saturated.prj

...ta/RichardsMechanics/flow_fully_saturated_anisotropic.prj

...hardsMechanics/flow_fully_saturated_coordinate_system.prj

Tests/Data/RichardsMechanics/flow_fully_saturated_linear.prj

Tests/Data/RichardsMechanics/gravity.prj

Tests/Data/RichardsMechanics/mechanics_linear.prj

Tests/Data/RichardsMechanics/orthotropic_swelling_xy.prj

Tests/Data/RichardsMechanics/orthotropic_swelling_xyz.prj

Tests/Data/RichardsMechanics/rotated_consolidation.prj