nan_by_qartod does not handle mishaps

Some OOI datasets may contain unexpected qartod flags which xarray interprets as objects (e.g. b'11', and b'13').
It is unclear what these values indicate. They are not QARTOD flags nor can an assumption be made if they reflect a primary flag or about the order of tests.

Currently, the nan_by_qartod function does not consider if the qartod test was executed and only considers results.