mitkSetupCPack.cmake checks the expected root folder for the redist executables and if a single directory is found, the redist executable is automatically set (it still can be done manually in CMake, though). The automatic logic does not work anymore because MS recently added another subfolder.
Instead of fixing it, we should actually remove all of this because it shouldn't be necessary at all. The InstallRequiredSystemLibraries module is included in the same file that will install the necessary runtime DLLs right besides our executables anyways.
This line is quite old and it may not have worked in the past as expected, or, as I found out, it wasn't configured correctly at least regarding OpenMP.
While working on this file, we should also make the NSIS generator optional to reduce the packaging time by half if a zip archive is enough.