chore: remove std.debug.print output from tests

[inge4pres]

Describe the current state

When running zig build test the output contains error message from tests that are expected to fail.
The output can be confusing and it would be best if it's be isolated.

Describe the desired state

The tests output is flused into a temporary memory buffer.
It is not strictly necessary that it is usable for inspection, it would be a nice to have though, in case some tests want to assert on error messages.

Proposed solution

Replace std.debug.print calls with std.log and find a way to direct the log output to a memory buffer, ideally per-test.

[klaus82]

Hi @inge4pres can I start from this?

[inge4pres]

@klaus82 seems like the perfect one to get started!
Thanks 🙏🏼

[inge4pres]

There are some in-flight PRs that are still adding some std.debug.print calls, they're all on me though so I'll make sure to replace with whatever you come up to replace before merging, or update after merge.