Add Elasticsearch 6 support

Remove predefined version from formula
Start using states instead of modules in client.sls
Update test repos to mirror.mirantis.com
Update tests to use ES6
Disable all x-pack features

Change-Id: I7f5a65b0777f2ebce9bd3aae79888d2b00d428b6
Prod-Related: PROD-25122
20 files changed