Fix display of default xattr to show 'sa'

When the default value of the xattr property was changed from 'dir' to
'sa', the code that displays the property's value was not affected. The
problem with this state of affairs is that 1) user tooling that
specifically looked for 'sa' before will be confused now that the code
displays 'on' instead. And 2) users may be confused when manually
running the commands about which specific type of xattr is in use unless
they are up to date on the latest zfs changes.

The fix here is to show the actual type always, rather than 'on' if we
happen to be using the default. This turns out to be easy to do, by
simply reordering the list of xattr values in the properties code. When
the property is displayed, we iterate down the table until we find a row
with a matching value, and use that row's name as the
display. Reordering the row fixes the display without affecting any
other code.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Rob Norris <robn@despairlabs.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Paul Dagnelie <paul.dagnelie@klarasystems.com>
Closes #17801