The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
Ensure the client which access etcd via grpc-gateway won't
be limited by the MaxCallRecvMsgSize. Here we choose the same
default value of etcdcli as grpc-gateway's MaxCallRecvMsgSize.
Fix https://github.com/etcd-io/etcd/issues/12576