Fixed random failure of main.truncate_notembedded

The test depends on how the server allocates memory and may fail randomly.
Fixed by accepting that TRUNCATE may work in some cases (happened to me)

mysql-test/main/truncate_notembedded.result

@@ -13,7 +13,6 @@ a
 UNLOCK TABLES;
 connection con1;
 TRUNCATE TABLE t1;
-ERROR HY000: The MariaDB server is running with the --max-thread-mem-used=65536 option so it cannot execute this statement
 disconnect con1;
 connection default;
 DROP TABLE t1;

mysql-test/main/truncate_notembedded.test

@@ -19,7 +19,10 @@ UNLOCK TABLES;
 
 --connection con1
 --reap
---error ER_OPTION_PREVENTS_STATEMENT
+# This may work or fail as different servers uses different amount of
+# memory and the statement may work or not. What is important is that we
+# don't get a crash here!
+--error 0,ER_OPTION_PREVENTS_STATEMENT
 TRUNCATE TABLE t1;
 
 --disconnect con1