Review Flags pass to add_ippl_test

[biddisco]

Currently nearly all tests added to ippl unit testing are using default parameters and thus run using mpiexec/srun/etc launch - which can be resource consuming on the CI/CD framework. Many individual srun jobs causes slurm problems at CSCS and we are asked to use it sparingly in general.

Tests should be reviewed to ensure they only run as MPI jobs if they need to do so.

Adding the NO_MPI flag to the add_ippl_test(...) is all that is required

[aaadelmann]

Why do you think that tests that now run mpiexec/srun should NOT run in parallel? Is this not undermining the idea of thorrow CI/CD? Furthermore what are the problems CSCS is reporting?