Fix public-plugins symlinks when precompiling

This release includes a fix for the following:

• https://meta.discourse.org/t/mathjax-seems-broken-in-v2-9-0-beta5/231702

At precompiling time, ember execution creates symlinks under the public/plugins folder.

It also includes a bump for the origin-kube-rbac-proxy, from 4.9 to 4.10 (in view of the new OKD4.10 release happening this week).