1s failover time when the TiProxy VIP owner shuts down

[djshow832]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. Start a cluster with 2 TiProxy. TiProxy is configured with VIP.
2. Clients connect to the VIP.
3. Kill the TiProxy VIP owner.
4. Check the failover time from clients.

2. What did you expect to see? (Required)

RTO=0

3. What did you see instead (Required)

RTO=1s
The log shows that when the old owner is down, the client connects to the new owner, but reports invalid connection. I'm afraid even if the new owner has bound the VIP, it still rejects connections with this VIP.

4. What is your version? (Required)

main