remove TestProxyClose (#4005)
remove TestProxyClose (#4005)

Signed-off-by: zounengren <6930cd8d7eab0b52cb34a0610ba7cd21fe073fc5@cmss.chinamobile.com>
johnbelamaric/coredns,chrisohaver/coredns,coredns/coredns,miekg/coredns,johnbelamaric/coredns,yongtang/coredns,miekg/coredns