MDEV-18564: Change wsrep_load_data_splitting off by default

Variable wsrep_load_data_splitting is deprecated and should be off
by default.

mysql-test/suite/galera/r/galera_defaults.result

@@ -34,7 +34,7 @@ WSREP_FORCED_BINLOG_FORMAT	NONE
 WSREP_GTID_DOMAIN_ID	0
 WSREP_GTID_MODE	OFF
 WSREP_IGNORE_APPLY_ERRORS	7
-WSREP_LOAD_DATA_SPLITTING	ON
+WSREP_LOAD_DATA_SPLITTING	OFF
 WSREP_LOG_CONFLICTS	OFF
 WSREP_MAX_WS_ROWS	0
 WSREP_MAX_WS_SIZE	2147483647

mysql-test/suite/galera/r/galera_var_load_data_splitting.result

@@ -12,7 +12,11 @@ COUNT(*) = 95000
 wsrep_last_committed_diff
 1
 connection node_1;
-SET GLOBAL wsrep_load_data_splitting = 1;;
+SET GLOBAL wsrep_load_data_splitting = 0;;
+Warnings:
+Warning	1287	'@@wsrep_load_data_splitting' is deprecated and will be removed in a future release
+connection node_2;
+SET GLOBAL wsrep_load_data_splitting = 0;;
 Warnings:
 Warning	1287	'@@wsrep_load_data_splitting' is deprecated and will be removed in a future release
 DROP TABLE t1;

mysql-test/suite/galera/r/partition.result

@@ -159,7 +159,7 @@ wsrep_last_committed_diff
 AS_EXPECTED_1_or_2
 DROP TABLE t1;
 connection node_1;
-SET GLOBAL wsrep_load_data_splitting = 1;;
+SET GLOBAL wsrep_load_data_splitting = 0;;
 Warnings:
 Warning	1287	'@@wsrep_load_data_splitting' is deprecated and will be removed in a future release
 disconnect node_2;

mysql-test/suite/galera/t/galera_var_load_data_splitting.test

@@ -36,4 +36,7 @@ SELECT COUNT(*) = 95000 FROM t1;
 --connection node_1
 --eval SET GLOBAL wsrep_load_data_splitting = $wsrep_load_data_splitting_orig;
 
+--connection node_2
+--eval SET GLOBAL wsrep_load_data_splitting = $wsrep_load_data_splitting_orig;
+
 DROP TABLE t1;

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

@@ -227,9 +227,9 @@ READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	WSREP_LOAD_DATA_SPLITTING
 SESSION_VALUE	NULL
-GLOBAL_VALUE	ON
+GLOBAL_VALUE	OFF
 GLOBAL_VALUE_ORIGIN	COMPILE-TIME
-DEFAULT_VALUE	ON
+DEFAULT_VALUE	OFF
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	BOOLEAN
 VARIABLE_COMMENT	To commit LOAD DATA transaction after every 10K rows inserted (deprecated)

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

@@ -6,7 +6,7 @@ SET @wsrep_load_data_splitting_global_saved = @@global.wsrep_load_data_splitting
 # default
 SELECT @@global.wsrep_load_data_splitting;
 @@global.wsrep_load_data_splitting
-1
+0
 
 # scope
 SELECT @@session.wsrep_load_data_splitting;
@@ -42,7 +42,7 @@ Warnings:
 Warning	1287	'@@wsrep_load_data_splitting' is deprecated and will be removed in a future release
 SELECT @@global.wsrep_load_data_splitting;
 @@global.wsrep_load_data_splitting
-1
+0
 
 # invalid values
 SET @@global.wsrep_load_data_splitting=NULL;

sql/sys_vars.cc

@@ -5540,7 +5540,7 @@ static Sys_var_mybool Sys_wsrep_load_data_splitting(
        "wsrep_load_data_splitting", "To commit LOAD DATA "
        "transaction after every 10K rows inserted (deprecated)",
        GLOBAL_VAR(wsrep_load_data_splitting), 
-       CMD_LINE(OPT_ARG), DEFAULT(TRUE), NO_MUTEX_GUARD, NOT_IN_BINLOG,
+       CMD_LINE(OPT_ARG), DEFAULT(0), NO_MUTEX_GUARD, NOT_IN_BINLOG,
        ON_CHECK(0), ON_UPDATE(0), DEPRECATED(""));
 
 static Sys_var_mybool Sys_wsrep_slave_FK_checks(