Consider hiding sample download for multi-pass problems #3281
Description
DOMjudge provides a samples.zip for each individual problem via the problemset page. This is disabled for interactive problems (#926), because the .in files are fed into the interactor, not the submission, and may thus contain additional information controlling the interactor's behaviour. The .ans files are usually empty for interactive problems. We typically provide a testing tool (which may use a different input format) and input files for the testing tool as attachments.
For multi-pass problems, a .in file is the input for the first pass of a submission, and the .ans file is typically (ab)used to control the multi-pass interactor's behaviour. Similar to interactive problems, these files should therefore be hidden from contestants, as they might be confusing or contain outright spoilers.
I think the cleanest solution would be to entirely disable the samples.zip for multi-pass problems. The .in files and a testing tool can then still be provided as attachments.
I should mention that the new problem package format allows explicitly creating files .in.download and .ans.download to override the .in and .ans files for purposes of downloads, see here: https://www.kattis.com/problem-package-format/spec/2025-09.html#samples-available-for-download
See also #2307 for previous discussion about multi-pass problems.