Retry Service SHOULD preserve server ID

[martinduke]

The Retry Service may not have the necessary state to encode server ID in the CID. But if it does, it SHOULD encode the same server ID in the new CID (assuming one is encoded)

[martinduke]

Upon further reflection, there's no reason for this. The only way the CID could be meaningful is if it came from a Retry -- in which case, there can't be another Retry.

To have any purpose at all, we have to imagine some future version or extension of QUIC where the server provides CIDs for subsequent connections. A little too speculative, I think.