This CallbackAsyncTuning freezes the ArchiveAsyncTuning to ArchiveAsyncTuningFrozen after the optimization has finished.
Examples
clbk("mlr3tuning.async_freeze_archive")
#> <CallbackAsyncTuning:mlr3tuning.async_freeze_archive>: Archive Freeze Callback
#> * Active Stages: on_optimization_end