Remove notes bugType?

Categorizing notes is sometimes very tricky, as some issues straddle the line. That takes time, and in my experience it was the slowest part of adding my ML-KEM vectors. Is that effort worth it? Does anyone use those categorizations? If not, we should remove them.

/cc @cpu

Start by locating where note and bugType categorizations are defined and consumed, especially around the ML-KEM vectors mentioned in the issue. No file or test is named, and completion requires an agreed decision about whether these categorizations are used before any implementation scope can be established.

Written by the indexing model from the issue text.