Three corrections to issue tests that had wrong assumptions about
when data becomes available:
1. initial_map_should_include_peer_online_status: use WaitForCondition
instead of checking the initial netmap. Online status is set by
Connect() which sends a PeerChange patch after the initial
RegisterResponse, so it may not be present immediately.
2. disco_key_should_propagate_to_peers: use WaitForCondition. The
DiscoKey is sent in the first MapRequest (not RegisterRequest),
so peers may not see it until a subsequent map update.
3. approved_route_without_announcement: invert the test expectation.
Tailscale uses a strict advertise-then-approve model -- routes are
only distributed when the node advertises them (Hostinfo.RoutableIPs)
AND they are approved. An approval without advertisement is a dormant
pre-approval. The test now asserts the route does NOT appear in
AllowedIPs, matching upstream Tailscale semantics.
Also fix TestClient.Reconnect to clear the cached netmap and drain
pending updates before re-registering. Without this, WaitForPeers
returned immediately based on the old session's stale data.
3d53f97c82