Follow-up: Introduce reduced KATs and/or ARM32 full run

[reneme]

          > Perhaps it makes sense to support some kind of "reduced" KAT tests (potentially generically for all PQC algorithms)?

Possibly so. I think CI runtimes are generally fine except for valgrind and the arm32 qemu (which for whatever reason is much slower than the other qemus) so it doesn't seem that pressing. The only possible issue is that we would miss an ARM32 specific bug since we never run those tests in CI. We could consider add a nightly similar to the valgrind full run.

Originally posted by @randombit in #4081 (comment)