Re-apply path sanitizer, as mount(8) still mangles it

Prior to util-linux 2.36.2, if a file or directory in the
current working directory was named 'dataset' then mount(8)
would prepend the current working directory to the dataset.

Eventually, we should be able to drop this workaround.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Sterling Jensen <sterlingjensen@users.noreply.github.com>
Closes #11295
Closes #11462