r70765: euptex \aftergroup \output routine fix, from branch2024

unbalanced-braces-eptex.ch : sync with the new unbalanced-braces.ch

git-svn-id: svn://tug.org/texlive/branches/branch2024/Build/source@70755 c570f23f-e606-0410-a88d-b1316a301751