docs/ci: Document envtest path when `make test` fails due to Docker credential helper (WSL/Docker Desktop)

[rich7420]

What happened?

Running make test fails before any Go tests run because the Makefile builds a Docker builder image (to run tests inside a container). The Docker pull step fails with:

ERROR: failed to solve: golang:1.24.4-bullseye: failed to resolve source metadata for docker.io/library/golang:1.24.4-bullseye: error getting credentials - err: exec: "docker-credential-desktop.exe": executable file not found in $PATH, out: ``

This occurs when:

• WSL (Windows Subsystem for Linux) is used with Docker Desktop: the Docker config in ~/.docker/config.json often references docker-credential-desktop.exe, which is a Windows executable and is not in $PATH when running make from a Linux shell in WSL.
• Other environments where the configured Docker credential helper is not available in the environment that runs make test.

What did you expect to happen?

• Either make test to succeed in WSL (and similar environments), or
• Clear documentation on how to run tests without Docker (e.g. unit tests via go test, integration tests via envtest) so CI and local workflows are reproducible.

Environment

• OS: Linux (WSL2), Windows host with Docker Desktop
• Docker: Docker Desktop with credential helper docker-credential-desktop.exe
• Reproduction: Run make test from WSL; builder image build fails on pull with the credential error above.

[davidLif]

Hello @rich7420,

Many of our Makefile command require docker installed as a prerequisit.
While I do think that we need to update the prerequistie in the "building-from-source.md" readme, I think it would be a bad idea to try and "fix" the users environment to make it work. It's the users responsibility to install docker and make it work in the environment he is using.

[gshaibi]

Re-labeling this as a documentation issue.