HttpClient used in RegistrationHelper should rely on STANDARD spec

The HttpClient configured in the class RegistrationHelper used the default factory org.apache.http.impl.client.HttpClients.createDefault which doesn't handle properly the RFC-6265 for the date format of the expires field. We should rely on a custom builder like defined in the method org.nuxeo.connect.connector.http.ConnectHttpConnector#execServer in order to use a different cookie specifications.
The issue has been revealed by the migration on pre-production to NOS deployed on NCP-5 using an ALB instead of an ELB as in the previous NOS stacks.