MDEV-8032 [PATCH] audit plugin - csv output broken.

Symbols like TAB or NEWLINE should be escaped, which was
        forgotten in one place.

mysql-test/suite/plugins/t/server_audit.test

@@ -35,6 +35,9 @@ insert into t2 values (1), (2);
 select * from t2;
 alter table t1 rename renamed_t1;
 set global server_audit_events='connect,query';
+select 1,
+        2,
+        3;
 insert into t2 values (1), (2);
 select * from t2;
 --error ER_NO_SUCH_TABLE