etcd connection leakage when reload

[Daseinlux]

What happened:
etcd connection leakage when reload.
What you expected to happen:

How to reproduce it (as minimally and precisely as possible):
use etcd plugin and modify corefile to trigger reload.
Anything else we need to know?:

Environment:

• the version of CoreDNS: v1.11.1
• Corefile:

  .:53 {
      errors
      health {
          lameduck 5s
      }
      ready
      etcd com {
          path /skydns/ka2
          endpoint http://192.168.0.1:2379 http://192.168.0.2:2379 http://192.168.0.3:2379
          fallthrough
      }
      cache 10
      loop
      reload
      log
      loadbalance
  }

• logs, if applicable:
• OS (e.g: cat /etc/os-release):
• Others:

[yangsenzk]

This bug can be reproduced. The process_open_fds metric of backend ETCD will be continuously increased by modify corefile that triggered coredns reload.