[CLEANUP] remove manually annoted legacy code

[chancancode]

These are slightly riskier in that you'd have to take the comment author's word for it, as the proposed code was never execrised or tested in the real world (unlike in #20798, where, if there were no bugs in the branchgin, we should have been running the correct branch all along and for a while now).

But I manually audited these spots and to my knowledge they seemed safe.