core: Fix ListenQUIC listener key conflict
core: Fix ListenQUIC listener key conflict

Reported on commit e3e8aabbcf65d37516bb97f9dc0f77df52f8cf55

Abused this change in some bash for loops to rapidly reload config
while making requests and didn't observe any memory or resource leaks.

l3dlp/caddy,l3dlp/caddy,l3dlp/caddy