revisit Compare Dataset Fields QA program

[cseppan]

The Compare Dataset Fields QA program can create very large database tables if inadvertently used instead of the Compare Datasets program. For now, this QA program has been removed from the list of available programs when creating a new QA step (commit 8145b85). This commit only modifies the list of QA Programs in the Add Custom QA Step window; it doesn't change the list of programs when editing an existing QA step or adding a QA Step Template to a dataset type.

In the future, we may want to add limit checks when setting up a Compare Dataset Fields QA step and then restore the program as an option.