MDEV-30620 Trying to lock uninitialized LOCK_parallel_entry

The error was seen by a number of mtr tests being caused
by overdue initialization of rpl_parallel::LOCK_parallel_entry.
Specifically, SHOW-SLAVE-STATUS might find in
rpl_parallel::workers_idle() a gtid domain hash entry
already inserted whose mutex had not done
mysql_mutex_init().

Fixed with swapping the mutex init and the its entry's stack insertion.

Tested with a generous number of `mtr --repeat` of a few of the reported
to fail tests, incl rpl.parallel_backup.

sql/rpl_parallel.cc

@@ -2312,14 +2312,16 @@ rpl_parallel::find(uint32 domain_id)
     e->domain_id= domain_id;
     e->stop_on_error_sub_id= (uint64)ULONGLONG_MAX;
     e->pause_sub_id= (uint64)ULONGLONG_MAX;
+    mysql_mutex_init(key_LOCK_parallel_entry, &e->LOCK_parallel_entry,
+                     MY_MUTEX_INIT_FAST);
+    mysql_cond_init(key_COND_parallel_entry, &e->COND_parallel_entry, NULL);
     if (my_hash_insert(&domain_hash, (uchar *)e))
     {
+      mysql_cond_destroy(&e->COND_parallel_entry);
+      mysql_mutex_destroy(&e->LOCK_parallel_entry);
       my_free(e);
       return NULL;
     }
-    mysql_mutex_init(key_LOCK_parallel_entry, &e->LOCK_parallel_entry,
-                     MY_MUTEX_INIT_FAST);
-    mysql_cond_init(key_COND_parallel_entry, &e->COND_parallel_entry, NULL);
   }
   else
     e->force_abort= false;