The embedded Elasticsearch HTTP must listen on port 9200

The default embedded ES uses range port (9200-9300)) for the HTTP protocol. This means that if port 9200 is already taken it uses port 9201.
The Nuxeo ES passthrough configuration is setup to use port 9200 so it is possible to use a wrong ES server.

To fix this embedded ES HTTP port must be 9200 and it should raise an error if the port is already taken.