also fix /bin/sync diversion for bullseye
When doing this in bookworm, we're in the unmerged case. Unfortunately, I added --no-rename, so now ln -sv sees that /bin/sync exists and fails.
The --no-rename was added, because renaming is ambiguous on merged-/usr, but we're in the unmerged case here, so use --rename.
Closes: #1068312 Fixes: 1b9a3843 ("also fix /bin/sync diversion for bookworm")