Fixes #8316: Removing a host can create a huge transaction

Removing a host with some reports (say 200), and each of them with several log lines (10000) generates 2.000.000 DELETE sql statements in the same transaction.
More often than not, ActiveRecord won't be able to make such a big transaction, in fact it will likely eat all memory available (I tried on a machine 16GB RAM machine) and Foreman will stop working in that host. In the best scenario the DB will end up with a non-committed giant transaction.

I suggest deleting hosts and reports manually on host destroy to avoid this.
But won't this hit limit of numbers that can reside in the "in" statement? If we can, we should really use nested queries (I have no clue how to do this in AR tho):

```sql
DELETE FROM logs
WHERE report_id IN 
    (SELECT id FROM reports
     WHERE log_id = ?)
```