Separate cluster client with singular .hosts config does not work

[chrisronline]

In monitoring, we create a separate cluster client connection for the monitoring cluster (which can be the same as the production cluster, or different). Config like:

monitoring.ui.elasticsearch.username: kibana
monitoring.ui.elasticsearch.password: changeme
monitoring.ui.elasticsearch.hosts: "http://localhost:8200"

Doesn't work because we expect hosts to be an array, which could be an issue how we merge configs too.

Config like:

monitoring.ui.elasticsearch.username: kibana
monitoring.ui.elasticsearch.password: changeme
monitoring.ui.elasticsearch.hosts: ["http://localhost:8200"]

works.

[elasticmachine]

Pinging @elastic/kibana-platform (Team:Platform)