ipatests: Fix on logs collection
If the function `install_kra` or `install_ca` fails
on call `host.run_command(command, raiseonerr=raiseonerr)`
then the logs are not collected.
This situation is not optimal because we need to see what happend
during the debbuging the tests.
So, this patch solves this situation and it adds try--finally
construction.
https://pagure.io/freeipa/issue/7214
Reviewed-By: Tomas Krizek <tkrizek@redhat.com>