Troponin-T uses `value`, should use `valuenum`

[alistairewj]

The cardiac marker concept grabs troponin-T:

https://github.com/MIT-LCP/mimic-code/blob/14b9f5f7c622f4535dd6da88969de3e2f2460904/mimic-iv/concepts/measurement/cardiac_marker.sql#L8

However almost every single value is ___ (due to the deidentification), so the derived table has all empty values. The valuenum column has the actual data however, so we should change the code to use valuenum instead.