MDEV-19370: rpl.kill_race_condition failed in buildbot with Wrong value for slave parameter

Problem:
=======
Executing test with following options will result in test failure.

./mtr rpl.kill_race_condition{,,,,,,,,,,} --repeat=10 --par 12 --mem

Fix:
====
Test simulates applier thread kill scenario while applying a row event.  But it
doesn't wait for applier to catch the error stop.

Added :wait_for_slave_sql_error.inc to catch the error.

Test uses START SLAVE as a final step and doesn't wait for both threads to
start.

Added: start_slave.inc

mysql-test/suite/rpl/r/kill_race_condition.result

 include/master-slave.inc
 [connection master]
-set global debug_dbug='d,rows_log_event_before_open_table';
-set debug_sync='now WAIT_FOR before_open_table';
 create table t1 (a int);
+set global debug_dbug='d,rows_log_event_before_open_table';
 insert t1 values (1),(2),(3);
+set debug_sync='now WAIT_FOR before_open_table';
 kill slave_sql_thread;
 set debug_sync='now SIGNAL go_ahead_sql';
+include/wait_for_slave_sql_error.inc [errno=1927]
+Last_SQL_Error = Error executing row event: 'Connection was killed'
 set global debug_dbug='';
 set debug_sync='RESET';
 drop table t1;
-start slave;
+include/start_slave.inc
+Last_SQL_Error = 
 include/rpl_end.inc

mysql-test/suite/rpl/t/kill_race_condition.test

@@ -2,27 +2,34 @@ source include/have_debug_sync.inc;
 source include/have_binlog_format_row.inc;
 source include/master-slave.inc;
 
+connection master;
+create table t1 (a int);
+--sync_slave_with_master
+
 connection slave;
 set global debug_dbug='d,rows_log_event_before_open_table';
-send set debug_sync='now WAIT_FOR before_open_table';
 
 connection master;
-create table t1 (a int);
 insert t1 values (1),(2),(3);
 
 connection slave;
-reap;
+set debug_sync='now WAIT_FOR before_open_table';
 let $a=`select id from information_schema.processlist where state='debug sync point: now'`;
 replace_result $a slave_sql_thread;
 eval kill $a;
 set debug_sync='now SIGNAL go_ahead_sql';
+--let $slave_sql_errno= 1927
+--source include/wait_for_slave_sql_error.inc
+let $error= query_get_value(SHOW SLAVE STATUS, Last_SQL_Error, 1);
+--echo Last_SQL_Error = $error
 set global debug_dbug='';
 set debug_sync='RESET';
-
 connection master;
 drop table t1;
 
 connection slave;
-start slave;
+--source include/start_slave.inc
+let $error= query_get_value(SHOW SLAVE STATUS, Last_SQL_Error, 1);
+--echo Last_SQL_Error = $error
 
 source include/rpl_end.inc;