This change should fix issue https://github.com/bitcoin/bitcoin/issues/33417
reported by zaidmstrr. It's possible to reproduce the `mp/proxy.capnp:0:
failed: Duplicate ID @0xcc316e3f71a040fb` error by installing libmultiprocess
system-wide, or to one of the locations listed in the python test's `imports`
list before the local libmultiprocess subtree, and then running the test.
Github-Pull: #33420
Rebased-From: e9c52272eb