update mesh paths (hyteg/!808)

hyteg_integration_tests/src/CurlCurl.cpp

hyteg_integration_tests/src/CurlCurlPlusMass.cpp

hyteg_integration_tests/src/DiffusionP1.cpp

hyteg_integration_tests/src/DiffusionP1Vector.cpp

hyteg_integration_tests/src/DiffusionP2.cpp

hyteg_integration_tests/src/Div.cpp

hyteg_integration_tests/src/DivKGrad.cpp

hyteg_integration_tests/src/DivT.cpp

hyteg_integration_tests/src/Epsilon.cpp

hyteg_integration_tests/src/EpsilonVector.cpp