ensure final dot on node name (#2503)

* ensure final dot on node name

This ensures that nodes which have a base domain set, will have a dot appended to their FQDN.

Resolves: https://github.com/juanfont/headscale/issues/2501

* improve OIDC TTL expire test

Waiting a bit more than the TTL of the OIDC token seems to remove some flakiness of this test. This furthermore makes use of a go func safe buffer which should avoid race conditions.

integration/dns_test.go

@@ -49,7 +49,7 @@ func TestResolveMagicDNS(t *testing.T) {
 			// It is safe to ignore this error as we handled it when caching it
 			peerFQDN, _ := peer.FQDN()
 
-			assert.Equal(t, fmt.Sprintf("%s.headscale.net", peer.Hostname()), peerFQDN)
+			assert.Equal(t, fmt.Sprintf("%s.headscale.net.", peer.Hostname()), peerFQDN)
 
 			command := []string{
 				"tailscale",