DevTools uses the wrong command to shut down an in-memory Derby database

```
2019-06-10 20:19:49.372  INFO 70310 --- [      Thread-32] o.s.b.f.support.DisposableBeanAdapter    : Invocation of destroy method failed on bean with name 'inMemoryDatabaseShutdownExecutor': java.sql.SQLSyntaxErrorException: Syntax error: Encountered "SHUTDOWN" at line 1, column 1.
```