MDEV-17484: New defaults for eq_range_index_dive_limit in 10.4

The default value for eq_range_index_dive_limit is set to 10

mysql-test/main/mysqld--help.result

@@ -1428,7 +1428,7 @@ encrypt-binlog FALSE
 encrypt-tmp-disk-tables FALSE
 encrypt-tmp-files FALSE
 enforce-storage-engine (No default value)
-eq-range-index-dive-limit 0
+eq-range-index-dive-limit 10
 event-scheduler OFF
 expensive-subquery-limit 100
 expire-logs-days 0

mysql-test/main/range_vs_index_merge.result

@@ -1079,7 +1079,7 @@ EXPLAIN SELECT Name, Country, Population FROM City WHERE
 (Name='Samara' AND Country='RUS') OR  
 (Name='Seattle' AND Country='USA');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	City	index_merge	Country,CountryPopulation,CountryName,CityName	CountryName,CityName	38,35	NULL	28	Using sort_union(CountryName,CityName); Using where
+1	SIMPLE	City	index_merge	Country,CountryPopulation,CountryName,CityName	CityName,CountryName	35,38	NULL	27	Using sort_union(CityName,CountryName); Using where
 SELECT Name, Country, Population FROM City WHERE
 (Name='Manila' AND Country='PHL') OR
 (Name='Addis Abeba' AND Country='ETH') OR          
@@ -1166,7 +1166,7 @@ EXPLAIN SELECT Name, Country, Population FROM City WHERE
 (Name='Samara' AND Country='RUS') OR  
 (Name='Seattle' AND Country='USA');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	City	range	Country,CountryPopulation,CountryName,CityName	CountryName	38	NULL	29	Using index condition; Using where
+1	SIMPLE	City	range	Country,CountryPopulation,CountryName,CityName	CountryName	38	NULL	27	Using index condition; Using where
 SELECT Name, Country, Population FROM City WHERE
 (Name='Manila' AND Country='PHL') OR
 (Name='Addis Abeba' AND Country='ETH') OR          
@@ -1922,6 +1922,6 @@ Country='POL' AND Name IN ('Warszawa', 'Wroclaw') OR
 Country='NOR' AND Name IN ('Oslo', 'Bergen') OR
 Country='ITA' AND Name IN ('Napoli', 'Venezia');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	City	range	CountryName,Name	CountryName	38	NULL	22	Using index condition; Using where
+1	SIMPLE	City	range	CountryName,Name	CountryName	38	NULL	20	Using index condition; Using where
 DROP DATABASE world;
 set session optimizer_switch='index_merge_sort_intersection=default';

mysql-test/suite/sys_vars/r/sysvars_server_embedded.result

@@ -881,10 +881,10 @@ ENUM_VALUE_LIST	NULL
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	NULL
 VARIABLE_NAME	EQ_RANGE_INDEX_DIVE_LIMIT
-SESSION_VALUE	0
-GLOBAL_VALUE	0
+SESSION_VALUE	10
+GLOBAL_VALUE	10
 GLOBAL_VALUE_ORIGIN	COMPILE-TIME
-DEFAULT_VALUE	0
+DEFAULT_VALUE	10
 VARIABLE_SCOPE	SESSION
 VARIABLE_TYPE	INT UNSIGNED
 VARIABLE_COMMENT	The optimizer will use existing index statistics instead of doing index dives for equality ranges if the number of equality ranges for the index is larger than or equal to this number. If set to 0, index dives are always used.

mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result

@@ -895,10 +895,10 @@ ENUM_VALUE_LIST	NULL
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	NULL
 VARIABLE_NAME	EQ_RANGE_INDEX_DIVE_LIMIT
-SESSION_VALUE	0
-GLOBAL_VALUE	0
+SESSION_VALUE	10
+GLOBAL_VALUE	10
 GLOBAL_VALUE_ORIGIN	COMPILE-TIME
-DEFAULT_VALUE	0
+DEFAULT_VALUE	10
 VARIABLE_SCOPE	SESSION
 VARIABLE_TYPE	INT UNSIGNED
 VARIABLE_COMMENT	The optimizer will use existing index statistics instead of doing index dives for equality ranges if the number of equality ranges for the index is larger than or equal to this number. If set to 0, index dives are always used.

sql/sys_vars.cc

@@ -2702,7 +2702,7 @@ static Sys_var_uint Sys_eq_range_index_dive_limit(
        "ranges for the index is larger than or equal to this number. "
        "If set to 0, index dives are always used.",
        SESSION_VAR(eq_range_index_dive_limit), CMD_LINE(REQUIRED_ARG),
-       VALID_RANGE(0, UINT_MAX32), DEFAULT(0),
+       VALID_RANGE(0, UINT_MAX32), DEFAULT(10),
        BLOCK_SIZE(1));
 
 static Sys_var_ulong Sys_range_alloc_block_size(