
The one remaining caller of peerMap.endpointForDiscoKey was making the improper assumption that there's exactly 1 node with a given DiscoKey in the network. That was the cause of #3088. Now that all the other callers have been updated to not use endpointForDiscoKey, there's no need to try to keep maintaining that prone-to-misuse index. Updates #3088 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>