ZTS: Fix problem with zdb_objset_id test
Use large numbers for datasets with numeric names to avoid name
and id collisions. Sporadic test failures were observed when the
test would create $TESTPOOL/100 with an objset ID of 100.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Zuchowski <pzuchowski@datto.com>
Closes #13087