wgengine/magicsock: handle wireguard only clean up and log messages

This change updates log messaging when cleaning up wireguard only peers.
This change also stops us unnecessarily attempting to clean up disco
pings for wireguard only endpoints.

Updates #7826

Signed-off-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>

wgengine/magicsock/endpoint.go

@@ -1335,8 +1335,12 @@ func (de *endpoint) stopAndReset() {
 	defer de.mu.Unlock()
 
 	if closing := de.c.closing.Load(); !closing {
+		if de.isWireguardOnly {
+			de.c.logf("[v1] magicsock: doing cleanup for wireguard key %s", de.publicKey.ShortString())
+		} else {
 			de.c.logf("[v1] magicsock: doing cleanup for discovery key %s", de.discoShort())
 		}
+	}
 
 	de.debugUpdates.Add(EndpointChange{
 		When: time.Now(),
@@ -1359,9 +1363,11 @@ func (de *endpoint) resetLocked() {
 	for _, es := range de.endpointState {
 		es.lastPing = 0
 	}
+	if !de.isWireguardOnly {
 		for txid, sp := range de.sentPing {
 			de.removeSentDiscoPingLocked(txid, sp)
 		}
+	}
 }
 
 func (de *endpoint) numStopAndReset() int64 {