Core/NetworkIO: Prevent queueing more async operations when socket is already closed
Revert "Revert "Fixed possible mount abuse after leaving bg""

This reverts commit 7d5077078097812ef20cc1bbeb4f6bfe40f3fb26.
Merge branch 'master' of https://github.com/TrinityCore/TrinityCore into ghbb
Merge branch 'master' of https://github.com/TrueWoW/TrinityCore into ghbb