Revert "clean up identifiers defined in `Main` (#51411)" (#51825)
This reverts commit ab94a242f6e56438f86a1babab7721db45b7feed.
Ref
https://github.com/JuliaLang/julia/pull/51411#issuecomment-1765402688
fixes https://github.com/JuliaLang/julia/issues/51823
