MDEV-30518: main.func_json_notembedded fails on s390x

MDEV-24909 added a json_pause_execution syncpoint however the test case
used debug_max_statement_time, which doesn't exist.

Fix the sync point name in the test.

Author: grooverdan

mysql-test/main/func_json_notembedded.result

@@ -11,7 +11,7 @@ length(@obj)	length(@arr)
 5000009	5000009
 set max_statement_time=0.0001;
 SET @old_debug= @@debug_dbug;
-SET debug_dbug='+d,debug_max_statement_time exceeded';
+SET debug_dbug='+d,json_pause_execution';
 select json_array_append(@arr, '$[0]', 1);
 ERROR 70100: Query execution was interrupted (max_statement_time exceeded)
 select json_array_insert(@arr, '$[0]', 1);

mysql-test/main/func_json_notembedded.test

@@ -18,7 +18,7 @@ select length(@obj), length(@arr);
 set max_statement_time=0.0001;
 disable_abort_on_error;
 SET @old_debug= @@debug_dbug;
-SET debug_dbug='+d,debug_max_statement_time exceeded';
+SET debug_dbug='+d,json_pause_execution';
 select json_array_append(@arr, '$[0]', 1);
 select json_array_insert(@arr, '$[0]', 1);
 select json_insert(@obj, '$.meta', 1);