Connection to multiple instances doesn't shutdown EventLoopGroup by finishing the work

[SamVicV]

• Issue: Service discovery client connects to Tarantool via the library protocol. After the client close the connection it has have an unclosed connection NioEventLoop (nioEventLoopGroup) from BinaryDiscoveryClusterAddressProvider.client.

cartridge-java version: 0.12.1

• Solving: It has to be added the closing of the client.

BinaryDiscoveryClusterAddressProvider.java

@Override
public void close() {
    super.close();
    try {
        client.close();
    } catch (Exception e) {
        throw new TarantoolClientException(e);
    }
}