MDEV-33751 Assertion `thd' failed in int temp_file_size_cb_func(tmp_file_tracking*, int)

Changes:
- Fixed that MyISAM and Aria parallel repair works with tmp file limit.
  This required to add current_thd to all parallel workers and add
  protection in my_malloc_size_cb_func() and temp_file_size_cb_func() to
  be able to handle shared THD's.  I removed the old code in MyISAM to
  set current_thd() as only worked when using with virtal indexed
  columns and I wanted to keep the Aria and MyISAM code identical.

Other things:
- Improved error messages from Aria parallel repair and
  create_internal_tmp_table_from_heap().

sql/sql_class.h

@@ -3127,6 +3127,8 @@ public:
   Trans_binlog_info *semisync_info;
   /* If this is a semisync slave connection. */
   bool semi_sync_slave;
+  /* Several threads may share this thd. Used with parallel repair */
+  bool shared_thd;
   ulonglong client_capabilities;  /* What the client supports */
   ulong max_client_packet_length;