Provide all libraries also without OpenMP

• The Octopus CI will likely soon need all libraries without OpenMP (to simplify tracking down numerical fluctuations and exclude fluctuation effects from third-party libraries)
• We already provide elpa+openmp and elpa~openmp in the 25a toolchains, the lmod module name is adjusted accordingly: elpa+openmp -> elpa-openmp module (with suffix)
• We need to choose a systematic naming scheme (e.g. either -openmp or -serial) and add both variants to all toolchains