Remove mpirun_workaround.sh (#1698)

Seems to no longer be necessary in the affected CI runs

Author: franzpoeschel

.github/workflows/linux.yml

@@ -328,8 +328,7 @@ jobs:
           -DopenPMD_USE_MPI=ON    \
           -DopenPMD_USE_HDF5=ON   \
           -DopenPMD_USE_ADIOS2=ON \
-          -DopenPMD_USE_INVASIVE_TESTS=ON \
-          -DMPIEXEC_EXECUTABLE=".github/workflows/mpirun_workaround.sh"
+          -DopenPMD_USE_INVASIVE_TESTS=ON
         cmake --build build --parallel 2
         cd build
         ctest --output-on-failure

.github/workflows/macos.yml

@@ -40,8 +40,7 @@ jobs:
           -DopenPMD_USE_MPI=ON    \
           -DopenPMD_USE_HDF5=ON   \
           -DopenPMD_USE_ADIOS2=ON \
-          -DopenPMD_USE_INVASIVE_TESTS=ON \
-          -DMPIEXEC_EXECUTABLE=".github/workflows/mpirun_workaround.sh"
+          -DopenPMD_USE_INVASIVE_TESTS=ON
         cmake --build build --parallel 3
         ctest --test-dir build --verbose