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.

hscontrol/types/node.go

@@ -364,7 +364,7 @@ func (node *Node) GetFQDN(baseDomain string) (string, error) {
 
 	if baseDomain != "" {
 		hostname = fmt.Sprintf(
-			"%s.%s",
+			"%s.%s.",
 			node.GivenName,
 			baseDomain,
 		)