add back missing default env vars from openshift proxy config, if present

[shalberd]

/kind feature

Why you need this feature:
During the last round of updates related to CA trust, code was removed that looks for an openshift central proxy config and adds the centrally configured values for HTTP_PROXY, HTTPS_PROXY, NO_PROXY

This is what used to be in there before:
186106

Describe the solution you'd like:
Take the old code, leave out trusted CA related stuff (no volume mounts, no setting CA trust related env vars as that happens elsewhere now.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]