This commit prevents us from repeatedly extending the lifetimes of all observed
addresses if a peer keeps on reconnecting.

It also fixes two race conditions:

1. We may end up processing a disconnect after a re-connect and may
accidentally give the addresses associated with that peer a
RecentlyConnectedAddrTTL instead of a ConnectedAddrTTL.

2. We may end up processing a connect after the associated disconnect storing
the associated peer addresses indefinitely.