[TaskGroup] reorder resumeWaiting->run and reenable async_taskgroup_discarding_dontLeak#67787

ktoso wants to merge 2 commits intomainswiftlang/swift:mainfrom

wip-task-group-unlock-then-run-cleanupsswiftlang/swift:wip-task-group-unlock-then-run-cleanupsCopy head branch name to clipboard