Starting a LAN with cheats enabled doesn't enable cheats for the initial player

Steps to reproduce:

1. Open a new survival world with cheats disabled
2. Click Open to LAN and enable cheats
3. Notice you can still not use OP commands

Notes:

• I haven't been able to test whether or not new players will have cheats enabled, feel free to do so
• This might be intended to stop players from cheating in a world with cheats disabled