Cluster settings: dark theme has unreadable color for cluster versions

[mdujava]

In dark theme, numbers over the nodes in graph on cluster settings page have black color on dark background, which is hard to read.

Looks like this line is resetting the color:

https://github.com/openshift/console/blob/e26ca04af6de6e08fe4fa1bbd8286053f6ff8a6a/frontend/public/components/cluster-settings/_cluster-settings.scss#L145

Observed on OpenShift 4.11.6