But how is this important? If the thing you're optimizing for is "total Go binary size", then all that matters is the total size of binary! How bytes are organized internally is irrelevant to this metric.
You should redo the analysis where you compile an old version of Cockroach DB (say v1.0.0) with Go versions 1.8 through 1.16, and then see what the numbers say. Your current analysis, which doesn't account for growth in the code base at all, or tries to account for it by deep-diving into the internal organization of the binary, is not sound.