[T] RM; Add pressure_interpolated to 2d_small refs

ProcessLib/RichardsMechanics/Tests.cmake

...Mechanics/RichardsFlow_2d_small_pcs_0_ts_0_t_0.000000.vtu

...nics/RichardsFlow_2d_small_pcs_0_ts_104_t_2000.000000.vtu

...hanics/RichardsFlow_2d_small_pcs_0_ts_19_t_318.000000.vtu

...Mechanics/RichardsFlow_2d_small_pcs_0_ts_1_t_1.000000.vtu

...hanics/RichardsFlow_2d_small_pcs_0_ts_29_t_518.000000.vtu

...Mechanics/RichardsFlow_2d_small_pcs_0_ts_2_t_3.000000.vtu

...hanics/RichardsFlow_2d_small_pcs_0_ts_39_t_718.000000.vtu

...Mechanics/RichardsFlow_2d_small_pcs_0_ts_3_t_8.000000.vtu

...hanics/RichardsFlow_2d_small_pcs_0_ts_49_t_918.000000.vtu

...echanics/RichardsFlow_2d_small_pcs_0_ts_4_t_18.000000.vtu

...anics/RichardsFlow_2d_small_pcs_0_ts_59_t_1118.000000.vtu

...echanics/RichardsFlow_2d_small_pcs_0_ts_5_t_38.000000.vtu

...anics/RichardsFlow_2d_small_pcs_0_ts_69_t_1318.000000.vtu

...echanics/RichardsFlow_2d_small_pcs_0_ts_6_t_58.000000.vtu

...anics/RichardsFlow_2d_small_pcs_0_ts_79_t_1518.000000.vtu

...echanics/RichardsFlow_2d_small_pcs_0_ts_7_t_78.000000.vtu

...anics/RichardsFlow_2d_small_pcs_0_ts_89_t_1718.000000.vtu

...echanics/RichardsFlow_2d_small_pcs_0_ts_8_t_98.000000.vtu

...anics/RichardsFlow_2d_small_pcs_0_ts_99_t_1918.000000.vtu