There's is currently, not a separate standalone-teiid-ha.xml configuration file. However, this is a teiid-ha installation script to use: teiid-standalone-ha-mode-install.cli
You would need to start the server without specifying the -c option. Then would need to install teiid: ./jboss-cli.sh --connect --file=./scripts/teiid-standalone-ha-mode-install.cli
Hope that helps.
Note that when cluster in standalone ha mode, the configuration is independent at each node. i.e. every node can have different configuration like vdbs, data sources and configuration is not automatically replicated. Domain mode gives you that.