fix: Ensure transport connection events don't act if duplicated#3863

EmandM wants to merge 5 commits intodevelop-2.0.0Unity-Technologies/com.unity.netcode.gameobjects:develop-2.0.0from

fix/multiple-transport-connection-eventsUnity-Technologies/com.unity.netcode.gameobjects:fix/multiple-transport-connection-eventsCopy head branch name to clipboard