Fixed costs in JOIN_TAB::estimate_scan_time() and HEAP

MDEV-35958 Cost estimates for materialized derived tables are poor

(Backport 11.8->11.4, the same patch)

Estimate_scan_time() calculates the cost of scanning a derivied table.
The old code did not take into account that the temporary table heap table
may be converted to Aria.

Things fixed:
- Added checking if the temporary tables data will fit in the heap.
  If not, then calculate the cost based on the designated internal
  temporary table engine (Aria).
- Removed MY_MAX(records, 1000) and instead trust the optimizer's
  estimate of records. This reduces the cost of temporary tables a bit
  for small tables, which caused a few changes in mtr results.
- Fixed cost calculation for HEAP.
  - HEAP costs->row_next_find_cost was not set. This does not affect old
    costs calculation as this cost slot was not used anywhere.
    Now HEAP cost->row_next_find_cost is set, which allowed me to remove
    some duplicated computation in ha_heap::scan_time()

Reviewed by: Sergei Petrunia <sergey@mariadb.com>

Author: montywi

mysql-test/main/cte_recursive.result

@@ -3913,8 +3913,8 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 1	PRIMARY	<derived3>	ref	key0	key0	23	test.t1.a1	1	FirstMatch(t1)
 3	DERIVED	t2	const	PRIMARY	PRIMARY	22	const	1	Using index
-4	RECURSIVE UNION	tt2	ALL	b1	NULL	NULL	NULL	14	Using where
-4	RECURSIVE UNION	<derived3>	ref	key0	key0	23	test.tt2.b1	1	
+4	RECURSIVE UNION	<derived3>	ALL	NULL	NULL	NULL	NULL	2	Using where
+4	RECURSIVE UNION	tt2	ref	b1	b1	23	cte.a2	1	
 NULL	UNION RESULT	<union3,4>	ALL	NULL	NULL	NULL	NULL	NULL	
 analyze format=json select fv
 from (select t1.a1, f1(t1.a2) fv from t1) dt
@@ -4013,38 +4013,37 @@ ANALYZE
                       "nested_loop": [
                         {
                           "table": {
-                            "table_name": "tt2",
+                            "table_name": "<derived3>",
                             "access_type": "ALL",
-                            "possible_keys": ["b1"],
                             "loops": 1,
                             "r_loops": 1,
-                            "rows": 14,
-                            "r_rows": 14,
+                            "rows": 2,
+                            "r_rows": 1,
                             "cost": "REPLACED",
                             "r_table_time_ms": "REPLACED",
                             "r_other_time_ms": "REPLACED",
-                            "r_engine_stats": REPLACED,
                             "filtered": 100,
                             "r_filtered": 100,
-                            "attached_condition": "tt2.b1 is not null"
+                            "attached_condition": "cte.a2 is not null"
                           }
                         },
                         {
                           "table": {
-                            "table_name": "<derived3>",
+                            "table_name": "tt2",
                             "access_type": "ref",
-                            "possible_keys": ["key0"],
-                            "key": "key0",
+                            "possible_keys": ["b1"],
+                            "key": "b1",
                             "key_length": "23",
-                            "used_key_parts": ["a2"],
-                            "ref": ["test.tt2.b1"],
-                            "loops": 14,
-                            "r_loops": 14,
+                            "used_key_parts": ["b1"],
+                            "ref": ["cte.a2"],
+                            "loops": 2,
+                            "r_loops": 1,
                             "rows": 1,
-                            "r_rows": 0.071428571,
+                            "r_rows": 1,
                             "cost": "REPLACED",
                             "r_table_time_ms": "REPLACED",
                             "r_other_time_ms": "REPLACED",
+                            "r_engine_stats": REPLACED,
                             "filtered": 100,
                             "r_filtered": 100
                           }