WL#10128:  Add defaults column to optimizer cost tables

ALTER TABLE mysql.server_cost DROP COLUMN default_value;
ALTER TABLE mysql.engine_cost DROP COLUMN default_value;
# restart:--upgrade=FORCE
SELECT * FROM mysql.server_cost;
cost_name	cost_value	last_update	comment	default_value
disk_temptable_create_cost	NULL	#	NULL	20
disk_temptable_row_cost	NULL	#	NULL	0.5
key_compare_cost	NULL	#	NULL	0.05
memory_temptable_create_cost	NULL	#	NULL	1
memory_temptable_row_cost	NULL	#	NULL	0.1
row_evaluate_cost	NULL	#	NULL	0.1
SELECT * FROM mysql.engine_cost;
engine_name	device_type	cost_name	cost_value	last_update	comment	default_value
default	0	io_block_read_cost	NULL	#	NULL	1
default	0	memory_block_read_cost	NULL	#	NULL	0.25
# Default values after upgrade should be equal to fresh server
include/assert.inc [Default values after upgrade should be equal to fresh server.]
# restart:--upgrade=FORCE
SELECT * FROM mysql.server_cost;
cost_name	cost_value	last_update	comment	default_value
disk_temptable_create_cost	NULL	#	NULL	20
disk_temptable_row_cost	NULL	#	NULL	0.5
key_compare_cost	NULL	#	NULL	0.05
memory_temptable_create_cost	NULL	#	NULL	1
memory_temptable_row_cost	NULL	#	NULL	0.1
row_evaluate_cost	NULL	#	NULL	0.1
SELECT * FROM mysql.engine_cost;
engine_name	device_type	cost_name	cost_value	last_update	comment	default_value
default	0	io_block_read_cost	NULL	#	NULL	1
default	0	memory_block_read_cost	NULL	#	NULL	0.25
# Default values after upgrade should be equal to fresh server
include/assert.inc [Default values after upgrade should be equal to fresh server.]