With 2.0, we now bind to `localhost` by default instead of binding to the network card and use its IP address.
When the discovery plugin gets from AWS API the list of nodes that should form the cluster, this list is pinged then. But as each node is bound to `localhost`, ping does not get an answer and the node elects itself as the master node.
`network.host` must be set.
Closes#13589.
Until now we had a cloud-aws plugin which is providing 2 disctinct features:
* discovery on EC2
* snapshot/restore on S3
This commit splits the plugin by feature so people can use either one or the other or both features.
Doc is updated accordingly.