fix: emit 'listening' when relays change

[achingbrain]

To signal to the rest of libp2p that our addresses are changing, emit the listening event when relays go away or our reservation expires.

Also remove the old tags on startup to ensure we don't reconnect to old relays as the spec says the reservation is only valid while we are connected.

Change checklist

• [x] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation if necessary (this includes comments as well)
• [x] I have added tests that prove my fix is effective or that my feature works