Remove MPI_Init from IndexRearrangementForStreamsTest

A Communicator is now passed to IndexRearrangementForStreams (Commit #7e1ef552). In the constructor of this Communicator MPI_Init is called. Therefore, an additional call to MPI_Init is not needed anymore.

src/gpu/VirtualFluids_GPU/DataStructureInitializer/GridReaderGenerator/IndexRearrangementForStreamsTest.cpp

@@ -295,7 +295,6 @@ private:
     std::unique_ptr<IndexRearrangementForStreams> createTestSubjectReorderSendIndices()
     {
         logging::Logger::addStream(&std::cout);
-        MPI_Init(NULL, NULL);
 
         SPtr<GridImpDouble> grid =
             GridImpDouble::makeShared(nullptr, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0, Distribution(), 1);