Consolidate COPY operations into a single layer

[yeikel]

What are you trying to accomplish?

Builds on work like #13638 and consolidates the copy operations behind a builder

How will you know you've accomplished your goal?

Existing tests pass, we create less number of layers for the image

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.

[yeikel]

Hey @jeffwidman

What do you think about this approach?

I understand we don’t want to consolidate just for the sake of it, but this feels like a neat trick.

The idea came to me while working on #13515. I believe the added complexity is justified, and the extra builder shouldn’t increase build time since we need the base image to be pulled for the final image anyway. 👀

If this looks good, we can apply a similar change to the other ecosystems (or ask Copilot to generate them).

[yeikel]

Not strictly necessary for this PR but not big enough for a separate PR

Using as instead of AS leads to a docker linting warning that is noisy

WARN: FromAsCasing: 'as' and 'FROM' keywords' casing do not match