Incorrect replication strategy calculation in DescribeRing

[Michal-Leszczynski]

The way in which DescribeRing calculates keyspace replication strategy isn't always correct.

	// Detect replication strategy
	if len(ring.HostDC) == 1 {
		ring.Replication = LocalStrategy
	} else {
		ring.Replication = NetworkTopologyStrategy
		for _, tokens := range dcTokens {
			if tokens != len(resp.Payload) {
				ring.Replication = SimpleStrategy
				break
			}
		}
	}

E.g. this test fails when SimpleStrategy RF is greater than half of the nodes count:

	t.Run("keyspace replication strategy", func(t *testing.T) {
		h := newRepairTestHelper(t, session, defaultConfig())
		ctx, cancel := context.WithCancel(context.Background())
		defer cancel()

		if err := clusterSession.ExecStmt("CREATE KEYSPACE test_rf WITH replication = {'class': 'SimpleStrategy', 'replication_factor' : 4}"); err != nil {
			t.Fatal(err)
		}
		defer dropKeyspace(t, clusterSession, "test_rf")

		ring, err := h.Client.DescribeRing(ctx, "test_rf")
		if err != nil {
			t.Fatal(err)
		}

		t.Log("Replication strategy", ring.Replication)
		if ring.Replication != scyllaclient.SimpleStrategy {
			t.Fatal("Incorrect replication strategy")
		}
	})