[Infra UI] The "View metrics for host" option is not always shown

[sorantis]

Kibana version: 7.3.0

Describe the bug:
The "View metrics for host" dropdown item in the Actions dropdown for graphs in Metrics Explorer is not always shown. Depending on what is selected in the "graph per" input field, e.g. if host.name is selected, then the user can see the action, if host.hostname is selected, then it's not visible.

Steps to reproduce:

1. Choose some metrics to graph.
2. Fill in the "graph per" with host.hostname.
3. Click on the Actions dropdown for any graph.
4. Should be able to see the View metrics for host action, but it's not there.

Screenshots (if relevant):

[elasticmachine]

Pinging @elastic/infra-logs-ui

[simianhacker]

This is not a bug...View metrics for host is only displayed for host.name, container.id, and kubernetes.pod.uid because those are the KNOWN fields we use to link to the Metrics Detail page. It wouldn't be practical to link using every possible field because they won't always be valid.