Add distinction between `Primary Diagnosis` and `Case Control Status`

[anngvu]

Original comment:

not sure how Case Control Status adds anything if #13 diagnosis is completed

Typically, 'Primary Diagnosis' and 'Case Control Status' provide the same information, i.e. often we are are comparing disease vs. no disease. However, for pre-cancer studies, there might be no disease diagnosis for any of the individuals studied, but there still might be an internal case/control status based on risk factors. Or it's possible that case-control status is not really apparent until a later timepoint, when some individuals develop the disease.

[anngvu]

So "Case Control Status" removed in the common cohort clinical data, and the original comment says this was redundant anyway. So closing as make a distinction is now moot.