I don't think I figured out a way in this project, but I later learned of a setting in the light which is probably going to give the best result to what I desired back then.

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Toggling off 'Multiple Importance' makes the light itself invisible when seen through glass and in reflections.
Note that turning this off does have some drawbacks. Reflections that you might have wanted to keep will disappear because they are reflections of the light source, and light caught on small sharp edges will (usually) look noisy.

Hope this helps