Update output variables section in LiquidFlow prj files

Tests/Data/Parabolic/LiquidFlow/AxiSymTheis/axisym_theis.prj

.../LiquidFlow/Flux/2D/square_1.8e1_calculatesurfaceflux.prj

...ic/LiquidFlow/Flux/2D/square_1e1_calculatesurfaceflux.prj

.../Hex/Parallel/cuboid_1x1x1_hex_27_Dirichlet_Dirichlet.prj

...yramid/cuboid_1x1x1_pyramid_6000_calculatesurfaceflux.prj

...rabolic/LiquidFlow/Flux/cube_1e3_calculatesurfaceflux.prj

...Flow/SimpleSynthetics/XDMF/FunctionParameterTest_XDMF.prj

...etics/XDMF_compression_off/FunctionParameterTest_XDMF.prj