MyiSAM and Aria, indexes with prefix compression, where the first keypart
could be NULL - in this case they didn't expect the next key after the
not NULL key to be NULL.
Expect the first keypart of the next key to have zero length even
if store_not_null==1, this combination means keypart is NULL,
don't pack it.
also fixes MDEV-27340
Moved test from main suite to the new suites.
Move tests from maria/t and maria/r to maria
mysql-test/mysql-test-run.pl:
Added support for the new suites