Tests : 1 single executable vs multiple executables

[flomnes]

          this will produce two executable, one for each .cmake, i think it's not necessary;

having more exe to build as we add test is too costly, consider 1 exe for multiple unit translations

Originally posted by @a-zakir in https://github.com/AntaresSimulatorTeam/Antares_Simulator/pull/2391#discussion_r1758454622