Add responsivity to Cluster Environments table

Summary

In https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/15037 we added the ability to view Cluster Environments.

We used the table from gitlab-ui, however, the table is not yet styled correctly in its responsive (stacked) state. We need to enable responsiveness on the Cluster Environments table once gitlab-ui#357 (closed) is completed.