ZTS: Fix summary page creation again - second try

In PR #16599 I used 'return' like in C - which is wrong :/
This fix generates the summary as needed.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes #16611