Fix for timeout in rpl.rpl_parallel_retry

MDEV-17109 rpl.rpl_parallel_retry fails in buildbot with timeout

I was not able to prove that this fix works, but at least it simplifies
the problem as it removes some possible timing issues.

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

@@ -372,7 +372,7 @@ connection server_2;
 SET @old_dbug= @@GLOBAL.debug_dbug;
 SET @@GLOBAL.debug_dbug="+d,rpl_parallel_simulate_wait_at_retry";
 include/start_slave.inc
-# Make sure the 2nd seqno_1001 worker has gotten to waiting
+# Make sure both workers are waiting at their sync points
 # Signal to the 1st to proceed after it has reached termination state
 SET @@DEBUG_SYNC='now SIGNAL proceed_by_1000';
 connection spoiler_21;

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

@@ -426,8 +426,8 @@ SET @old_dbug= @@GLOBAL.debug_dbug;
 SET @@GLOBAL.debug_dbug="+d,rpl_parallel_simulate_wait_at_retry";
 --source include/start_slave.inc
 
---echo # Make sure the 2nd seqno_1001 worker has gotten to waiting
---let $wait_condition= SELECT count(*) FROM information_schema.processlist WHERE state LIKE '%debug sync point: now%';
+--echo # Make sure both workers are waiting at their sync points
+--let $wait_condition= SELECT count(*)=2 FROM information_schema.processlist WHERE state LIKE '%debug sync point%';
 --source include/wait_condition.inc