Let us avoid EXTENDED in the CHECK TABLE after a defragmentation,
because it would occasionally report an orphan delete-marked record
in the index "third". That error does not seem to be reproducible
when using the regular OPTIMIZE TABLE.

Also, let us make the test --repeat safe by removing the defragmentation
related statistics after DROP TABLE.

The defragmentation feature was removed in later releases in
commit 7ca89af6 (MDEV-30545)
along with this test case.