Velocity-CTD introduced the markLoginEventFired() method on ConnectedPlayer. Without calling this method, the login flow may not properly synchronize with Velocity-CTD's disconnect handling, leading to compatibility issues.

• Fix compatibility with Velocity-CTD by calling markLoginEventFired() on ConnectedPlayer via reflection before firing the LoginEvent
• Remove redundant DisconnectEvent firing when player disconnects during login, as Velocity-CTD's natural teardown path already handles this and prevents double-firing of disconnect events

Consistent with Velocity-CTD's login flow.