On FreeBSD 15 CURRENT, `ZREP_R=-R zrep sync <dataset>` also syncs `zrep:master`

[svmhdvn]

This causes an immediate split-brain situation.

Repro steps:

1. Start with ZREP_R=-R zrep init zroot/dataset host2 zroot/dataset
2. Then run ZREP_R=-R zrep sync zroot/dataset
3. Run zfs get zrep:written on the secondary host to observe that zrep:master is a received property and is set to yes