Update dev environment to work on CyberArk NG laptops

[diverdane]

What does this PR do?

On CyberArk dev laptops, golang module dependencies are downloaded with a corporate proxy in the middle. For these connections to succeed we need to configure the proxy CA certificate in build containers.

To allow build script to also work on non-CyberArk laptops where the CA certificate is not available, we copy the (potentially empty) directory into the build containers, and update container certificates based on that directory, rather than relying on the CA file itself.

What ticket does this PR close?

Checklists

Change log

• [ ] The CHANGELOG has been updated, or
• [x] This PR does not include user-facing changes and doesn't require a CHANGELOG update

Test coverage

• [ ] This PR includes new unit and integration tests to go with the code changes, or
• [x] The changes in this PR do not require tests

Documentation

• [x] This PR does not require updating any documentation, or
• [ ] Docs (e.g. READMEs) were updated in this PR, and/or there is a follow-on issue to update docs

(For releases only) Manual tests

• [ ] Manually run Kubernetes-Conjur demo with a local Secretless Broker image build of your branch

[codeclimate[bot]]

Code Climate has analyzed commit a1744400 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 53.6% (0.0% change).

View more on Code Climate.