allow_ddl option is not consistent over restarts

**version**
reproduced on 19.17.4.11 and latest 20.1.15.109

**Describe the bug**
My goal is to disable DDL operations for default profile.

I've created new profile with `allow_ddl: 1` and set `allow_ddl` to 0 for default profile.

clickhouse-server reloads config on the fly and now you can execute DDL with new profile. With default profile DDL queries fail as expected.

After restarting the clickhouse-server you can't execute DDL queries either by default profile or by new profile.

**How to reproduce**
simple demo
```
git clone https://gist.github.com/e95f89230004f3a6107f35f1a5bf8b56.git
bash run.sh
```