MDEV-11462: MariaRocks: rocksdb.type_float_indexes fails

Upadte test results (see jira entry for investigation about
the source of the differences)

storage/rocksdb/mysql-test/rocksdb/r/type_float_indexes.result

@@ -85,7 +85,7 @@ INSERT INTO t1 (f,r,d,dp,pk) VALUES
 (4644,1422.22,466664.999,0.5,5);
 EXPLAIN SELECT DISTINCT d FROM t1 ORDER BY d;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	d	d	9	NULL	#	Using index
+1	SIMPLE	t1	index	NULL	d	9	NULL	#	Using index
 SELECT DISTINCT d FROM t1 ORDER BY d;
 d
 -1
@@ -114,7 +114,7 @@ INSERT INTO t1 (f,r,d,dp,pk) VALUES
 (4644,1422.22,466664.999,0.5,5);
 EXPLAIN SELECT DISTINCT d FROM t1 ORDER BY d;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	d	d	9	NULL	#	Using index
+1	SIMPLE	t1	index	NULL	d	9	NULL	#	Using index
 SELECT DISTINCT d FROM t1 ORDER BY d;
 d
 -1
@@ -146,7 +146,7 @@ INSERT INTO t1 (f,r,d,dp,pk) VALUES
 ERROR 23000: Duplicate entry '1.2345' for key 'f'
 EXPLAIN SELECT DISTINCT f FROM t1 ORDER BY f;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	f	f	5	NULL	#	Using index
+1	SIMPLE	t1	index	NULL	f	5	NULL	#	Using index
 SELECT DISTINCT f FROM t1 ORDER BY f;
 f
 -1
@@ -177,7 +177,7 @@ INSERT INTO t1 (f,r,d,dp,pk) VALUES
 (1.2345,0,0,0,6);
 EXPLAIN SELECT DISTINCT f FROM t1 ORDER BY f;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	f	f	5	NULL	#	Using index
+1	SIMPLE	t1	index	NULL	f	5	NULL	#	Using index
 SELECT DISTINCT f FROM t1 ORDER BY f;
 f
 -1