Create an in-memory DNS server for ClientUtilsTest and ClusterConnectionStatesTest

ClientUtilsTest and ClusterConnectionStatesTest currently use an external DNS to resolve the IP addresses for kafka.apache.org. Until recently there were only two IP4 addresses, but now there is a third. 

At first the tests were changed to just check for multiple addresses. https://github.com/apache/kafka/pull/9294

However, these tests are pretty fragile when they rely on outside sources, so it would make sense to create an in-memory DNS.  This is what netty does for similar tests. 

 https://github.com/netty/netty/blob/master/resolver-dns/src/test/java/io/netty/resolver/dns/TestDnsServer.java.