itest: test for node ann persistence

This commit adds an itest that verify the behaviour of correctly
reusing persisted node ann configs across restarts. It also ensures
that the node ann configs are applied using the correct hierarchy.

itest/list_on_test.go

@@ -170,6 +170,10 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "update node announcement rpc",
 		TestFunc: testUpdateNodeAnnouncement,
 	},
+	{
+		Name:     "self node announcement persistence",
+		TestFunc: testSelfNodeAnnouncementPersistence,
+	},
 	{
 		Name:     "list payments",
 		TestFunc: testListPayments,