Properly remove entry from partition, close AsyncHttpClient#1461

Motivation:

DefaultChannelPool#removeAll fails to properly remove entry from
partition.

Modification:

Remove an `IdleChannel` instead of a `Channel`.

Result:

No more leak.

Author: slandelle

client/src/main/java/org/asynchttpclient/netty/channel/DefaultChannelPool.java

@@ -309,7 +309,7 @@ else if (isRemotelyClosed(idleChannel.channel)) {
      */
     public boolean removeAll(Channel channel) {
         ChannelCreation creation = connectionTtlEnabled ? channelId2Creation.remove(channelId(channel)) : null;
-        return !isClosed.get() && creation != null && partitions.get(creation.partitionKey).remove(channel);
+        return !isClosed.get() && creation != null && partitions.get(creation.partitionKey).remove(new IdleChannel(channel, Long.MIN_VALUE));
     }
 
     /**