Clear player lag compensator cache on disconnect

[jandrokt]

Description

Fixes an issue where a player's lag compensator cache would not be cleared after they disconnected.

How has this been tested?

I haven't tested it but it's simple enough.

Checklist:

• [x] I have reviewed my code thoroughly.
• [ ] I have tested my code.
• [x] My changes generate no new warnings

[Sculas]

Oh, I didn't notice that myself. That's a pretty bad memory leak I think. Anyway, thank you for this PR! :)