ipa-kra-install: fix check_host_keys
    
    ipa-kra-install on a replica checks that the keys are available before
    going further to avoid race condition due to replication. The issue is
    that the check_host_keys method expects to find exactly one key for
    cn=env/host but 2 may exist: one below cn=custodia and one below
    cn=dogtag,cn=custodia.
    The fix is to check that at least one key exist (not exactly one key).
    
    https://pagure.io/freeipa/issue/6934
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>