SET GLOBAL should not be stored in the session command history

While it is reasonable that SET GLOBAL is routed to all servers, they should not be stored in the session command history as they do not modify the state of the session but the global server state. In practice this is a waste of space but the worst-case scenario is that a session sets a global value that another connection later overwrites but a reconnection of the older session causes the global bariable to revert back to an older state.