fix: cleaning up connected clients upon shutdown [MTT-1573] (backport #1945)#1949

0xFA11 merged 5 commits intorelease/1.0.0Unity-Technologies/com.unity.netcode.gameobjects:release/1.0.0from

chore/client-cleanup-backportUnity-Technologies/com.unity.netcode.gameobjects:chore/client-cleanup-backportCopy head branch name to clipboard