Tiny cleanup: Move test pipelines to where others are. Remove unnecessary test packages.

[vaikas]

Move the pkg/test/pipelines/... into pkg/build/pipelines, so they get added as embedded pipelines into melange binary and there's no need to specify their location separately. This way it's consistent with the other pipelines.

wolfi-base has already a dependency on busybox, and there's no reason to include apk tools, just drop wolfi-base from the example tests for clarity and use busybox. For py3-pandas, the package should already have a dep on python, so don't add it into the tests also.

Melange Pull Request Template

Functional Changes

• This change can build all of Wolfi without errors (describe results in notes)

Notes:

SCA Changes

• Examining several representative APKs show no regression / the desired effect (details in notes)

Notes:

Linter

• The new check is clean across Wolfi
• The new check is opt-in or a warning

Notes: