fix sudo bug in check_mk::addhost

same issue as https://github.com/GRIF-IRFU/puppet-omd/pull/4 in `check_mk::addhost`. this patch fixes the reported issue.

```puppet
...
Debug: Executing 'sudo -i -u infra /opt/omd/sites/infra/bin/cmk -I HOST'
Notice: /Stage[main]/Monitoring/Omd::Check_mk::Addhost[HOST]/Exec[checkmk_inventory_HOST_infra]/returns: sudo: sorry, you must have a tty to run sudo
Error: /Stage[main]/Monitoring/Omd::Check_mk::Addhost[HOST]/Exec[checkmk_inventory_HOST_infra]: Failed to call refresh: sudo -i -u infra /opt/omd/sites/infra/bin/cmk -I HOST returned 1 instead of one of [0]
Error: /Stage[main]/Monitoring/Omd::Check_mk::Addhost[HOST]/Exec[checkmk_inventory_HOST_infra]: sudo -i -u infra /opt/omd/sites/infra/bin/cmk -I HOST returned 1 instead of one of [0]
...
```
(the actual hostname has been replaced with `HOST`)