types/opt: de-weird the API a bit with new True and False consts

Updates #cleanup

Change-Id: I15d8d840877d43e2b884d42354b4eb156094df7d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

tstest/integration/integration_test.go

@@ -1785,7 +1785,7 @@ func TestC2NDebugNetmap(t *testing.T) {
 	tstest.Shard(t)
 	tstest.Parallel(t)
 	env := NewTestEnv(t, ConfigureControl(func(s *testcontrol.Server) {
-		s.CollectServices = "false"
+		s.CollectServices = opt.False
 	}))
 
 	var testNodes []*TestNode

tstest/integration/testcontrol/testcontrol.go

@@ -1101,7 +1101,7 @@ func (s *Server) MapResponse(req *tailcfg.MapRequest) (res *tailcfg.MapResponse,
 		Node:            node,
 		DERPMap:         s.DERPMap,
 		Domain:          domain,
-		CollectServices: cmp.Or(s.CollectServices, "true"),
+		CollectServices: cmp.Or(s.CollectServices, opt.True),
 		PacketFilter:    packetFilterWithIngress(s.PeerRelayGrants),
 		DNSConfig:       dns,
 		ControlTime:     &t,