Revert "Fix incorrect expected error in ztest"

This reverts commit 2076011e0c4c2d8ad6a59534a4784a6aa5f4f3df. The
comment which explains EINVAL should be expected for this case was
wrong, not the code. The kernel will return ENOTSUP when attaching
a distributed spare to the wrong top-level dRAID vdev. See the
check for this in spa_vdev_attach().

Reviewed-by: Paul Dagnelie <paul.dagnelie@klarasystems.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #17503