MM-25256 don't idle timeout expire session on mobile (#14583)

app/session.go

@@ -75,7 +75,7 @@ func (a *App) GetSession(token string) (*model.Session, *model.AppError) {
 	}
 
 	if *a.Config().ServiceSettings.SessionIdleTimeoutInMinutes > 0 &&
-		!session.IsOAuth &&
+		!session.IsOAuth && !session.IsMobileApp() &&
 		session.Props[model.SESSION_PROP_TYPE] != model.SESSION_TYPE_USER_ACCESS_TOKEN &&
 		!*a.Config().ServiceSettings.ExtendSessionLengthWithActivity {