help request: control api of health check list non-exist upstream endpoint

[hitsub2]

Description

We see there are too many SYN_SENT conntracks in OS：

140391 SYN_SENT
36353 TIME_WAIT
187 CLOSE
142 ESTABLISHED

After dig into SYN_SENT and apisix healthchek dashboard, we found the RED upstream endpoint does not exist any more.

My question is:
1.How this happens
2.Why there is no refresh? etcd problem?

Environment

• APISIX version (run apisix version): 3.10
• Operating system (run uname -a): Bottlerocket
• OpenResty / Nginx version (run openresty -V or nginx -V):
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info): 3.5.13
• APISIX Dashboard version, if relevant:
• Plugin runner version, for issues related to plugin runners:
• LuaRocks version, for installation issues (run luarocks --version):