chore(shortint): add some flaky/failing doctests as actual tests

[IceTDrinker]

closes: https://github.com/zama-ai/tfhe-rs-internal/issues/323

PR content/description

• check that those are actually failing or that they are a doctest bug
• add _ci_run_filter so that we can easily make sure tests run in CI even if they don't have the "parameter format"

Check-list:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• Relevant issues are marked as resolved/closed, related issues are linked in the description
• Check for breaking changes (including serialization changes) and add them to commit message following the conventional commit specification

[github-actions]

@slab-ci cpu_fast_test

[tmontaigu]

And if we see that the actual are not flaky, we remove the doctest / mark them as ignored so that they don't run ?

[IceTDrinker]

And if we see that the actual are not flaky, we remove the doctest / mark them as ignored so that they don't run ?

Likely, and then ditch cargo doctest for our own doctest runner down the line I guess

[github-actions]

Pull Request has been approved 🎉
Launching full test suite...
@slab-ci cpu_test
@slab-ci cpu_integer_test
@slab-ci cpu_multi_bit_test
@slab-ci cpu_wasm_test
@slab-ci csprng_randomness_testing