[larsoner]

I tracked down some TODOs in our codebase and ironed them out:

1. read_raw_eximia had a real scaling bug for EEG and EOG data (uV vs V)
2. delete a redundant reset_bads call, and assert proper handling of reset_bads (and fix it for channels that were not interpolated)
3. remove crufty test_scaling=Falses where we can, add useful comments about why we can't where we don't
4. remove a qualname workaround now that 3.11 is our min
5. remove a "(maybe)" suggestion about making a change when 3.9 is our min (that we don't want to make)

Opus 5.5 helped me find these and draft changes, I reviewed and iterated on them.