MDEV-27575 Remove thd from spider_db_done

It is unused, and causing segfaults

storage/spider/mysql-test/spider/bugfix/r/mdev_27575.result

+#
+# MDEV-27575 Spider: UBSAN member access within null pointer of type 'struct st_plugin_int and SIGSEGV in intern_plugin_lock on SHUTDOWN when setting Spider as default storage engine (temporary or global)
+#
+for master_1
+for child2
+for child3
+SET GLOBAL default_tmp_storage_engine=spider;
+# restart
+SET GLOBAL default_storage_engine=Spider;
+# restart
+for master_1
+for child2
+for child3
+#
+# end of test mdev_27575
+#

storage/spider/mysql-test/spider/bugfix/t/mdev_27575.test

+--echo #
+--echo # MDEV-27575 Spider: UBSAN member access within null pointer of type 'struct st_plugin_int and SIGSEGV in intern_plugin_lock on SHUTDOWN when setting Spider as default storage engine (temporary or global)
+--echo #
+--disable_query_log
+--disable_result_log
+--source ../../t/test_init.inc
+--enable_result_log
+--enable_query_log
+
+SET GLOBAL default_tmp_storage_engine=spider;
+--source include/restart_mysqld.inc
+
+SET GLOBAL default_storage_engine=Spider;
+--source include/restart_mysqld.inc
+
+--disable_query_log
+--disable_result_log
+--source ../../t/test_deinit.inc
+--enable_result_log
+--enable_query_log
+--echo #
+--echo # end of test mdev_27575
+--echo #

storage/spider/spd_table.cc

@@ -6451,26 +6451,13 @@ int spider_db_done(
   void *p
 ) {
   int roop_count;
-  bool do_delete_thd;
-  THD *thd = current_thd, *tmp_thd;
+  THD *tmp_thd;
   SPIDER_CONN *conn;
   SPIDER_INIT_ERROR_TABLE *spider_init_error_table;
   SPIDER_TABLE_MON_LIST *table_mon_list;
   SPIDER_LGTM_TBLHND_SHARE *lgtm_tblhnd_share;
   DBUG_ENTER("spider_db_done");
 
-  /* Begin Spider plugin deinit */
-  if (thd)
-    do_delete_thd = FALSE;
-  else
-  {
-    /* Create a thread for Spider plugin deinit */
-    thd = spider_create_thd();
-    if (!thd)
-      DBUG_RETURN(HA_ERR_OUT_OF_MEM);
-    do_delete_thd = TRUE;
-  }
-
   for (roop_count = SPIDER_DBTON_SIZE - 1; roop_count >= 0; roop_count--)
   {
     if (spider_dbton[roop_count].deinit)
@@ -6687,13 +6674,6 @@ int spider_db_done(
       ));
   }
 
-  /* End Spider plugin deinit */
-  if (do_delete_thd)
-    spider_destroy_thd(thd);
-
-/*
-DBUG_ASSERT(0);
-*/
   DBUG_RETURN(0);
 }