ipapython: Propagate KRB5Error exceptions on iterating ccache
    
    `ipapython.session_storage.get_data` iterates over
    credentials in a credential cache till `krb5_cc_next_cred` returns
    an error. This function doesn't expect any error on calling
    other kerberos foreign functions during iteration. But that can
    actually happen and KRB5Error exceptions stop an iteration while
    they should be propagated.
    
    With this change iteration will exactly stop on `krb5_cc_next_cred`
    error as it was supposed to be.
    
    Fixes: https://pagure.io/freeipa/issue/9519
    Signed-off-by: Stanislav Levin <slev@altlinux.org>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>