test: expose custom image options as env vars

[jackfrancis]

Reason for Change:

This PR enables the passing of the set of Kubernetes custom image values as env vars, so that custom image builds can be tested against any api model.

Issue Fixed:

Credit Where Due:

Does this change contain code from or inspired by another project?

• No
• Yes

If "Yes," did you notify that project's maintainers and provide attribution?

• No
• Yes

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

[acs-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jackfrancis

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• OWNERS [jackfrancis]

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[codecov]

Codecov Report

Merging #4244 (132aeb4) into master (661af28) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4244   +/-   ##
=======================================
  Coverage   72.07%   72.07%           
=======================================
  Files         141      141           
  Lines       21702    21702           
=======================================
  Hits        15642    15642           
  Misses       5103     5103           
  Partials      957      957           

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