ipatests: TestMultipleExternalCA: Create tempfiles on remote host
    
    Previously, `test_master_install_ca1` and `test_master_install_ca2`
    attempt to create tempdirs on local host and later write some
    content into the returned paths on remote host. This fails if
    a remote host is a local one.
    
    The existent `create_temp_file` function has been extended to
    support `suffix` option of `mktemp`.
    
    Fixes: https://pagure.io/freeipa/issue/9013
    Signed-off-by: Stanislav Levin <slev@altlinux.org>
    Reviewed-By: Mohammad Rizwan <myusuf@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>