Updates Dockerfile and make linuxbrew-test to provide full logs suitable for...

General MR

Summary

I just approved a renovate's minor change to the Dockerfile and on the way I realized I'd need to tweak both the Dockerfile and Makefile to enable the desired test. Here are those tweaks.

Note: The Dockerfile is not used for anything other than semi-automated linuxbrew testing. We still don't have a CI job verifying this stuff but make linuxbrew-test would suffice if we were willing to set up a Docker-in-docker pipeline job.

Relevant logs/screenshots

See !9 (merged) for an example result (direct comment link: !9 (comment 3020518))

Linked Issue

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Upgrade Notices

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