[CodeGen] remove instnamer dependency from test file; NFC

This file was originally added without instnamer at:
rL283716 / fe2b9b4f

But that was reverted and the test file reappeared with instnamer at:
rL285688 / 62f516f5

I'm not seeing any difference locally from checking nameless values,
so trying to remove a layering violation and see if that can
survive the build bots.