[TaskGroup] Reenable test and fix memory issue #67392

ktoso merged 2 commits intoswiftlang:mainswiftlang/swift:mainfrom

ktoso:wip-reenable-async_taskgroup_discarding_dontLeak_class_error.swiftktoso/swift:wip-reenable-async_taskgroup_discarding_dontLeak_class_error.swiftCopy head branch name to clipboard