Now that we support a more general `compile_time_purge_matching`, we can deprecate `compile_time_purge_level`. We chose the name `:level_lower_than` rather than `:level` for the matching key since all other matches are exact.
Now that we support a more general `compile_time_purge_matching`, we can deprecate `compile_time_purge_level`. We chose the name `:level_lower_than` rather than `:level` for the matching key since all other matches are exact.