zfs: fix "zfs receive" of interrupted stream without "-F" after r366180

The OpenZFS test suite revealed a regression with the changes made by
r366180 and r364974: "zfs recv" resuming and interrupted stream without -F
would refuse to run, complaining that "dataset exists".

Direct commit to stable/12 because head has moved to the OpenZFS code base.

Upstream issue: https://github.com/openzfs/zfs/issues/10995

Reviewed by: mmacy
MFC after: 3 days
MFC-with: 366180
Sponsored by: Axcient