MDEV-34515 fixup: innodb.innodb_defrag_concurrent fails

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.

mysql-test/suite/innodb/r/innodb_defrag_concurrent.result

@@ -75,7 +75,7 @@ disconnect con4;
 optimize table t1;
 Table	Op	Msg_type	Msg_text
 test.t1	optimize	status	OK
-check table t1 extended;
+check table t1;
 Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
 select count(*) from t1;
@@ -97,6 +97,7 @@ select count(stat_value) > 0 from mysql.innodb_index_stats where table_name like
 count(stat_value) > 0
 1
 drop table t1;
+delete from mysql.innodb_index_stats where table_name='t1';
 SET GLOBAL innodb_defragment_n_pages = @n_pages;
 SET GLOBAL innodb_defragment_stats_accuracy = @accuracy;
 SET GLOBAL innodb_stats_persistent = @sp;

mysql-test/suite/innodb/t/innodb_defrag_concurrent.test

@@ -124,7 +124,7 @@ disconnect con3;
 disconnect con4;
 
 optimize table t1;
-check table t1 extended;
+check table t1;
 
 select count(*) from t1;
 select count(*) from t1 force index (second);
@@ -136,6 +136,7 @@ select count(stat_value) > 0 from mysql.innodb_index_stats where table_name like
 select count(stat_value) > 0 from mysql.innodb_index_stats where table_name like '%t1%' and  stat_name  in ('n_leaf_pages_defrag');
 
 drop table t1;
+delete from mysql.innodb_index_stats where table_name='t1';
 
 # reset system
 SET GLOBAL innodb_defragment_n_pages = @n_pages;