Replace os.popen(sfind, ...) with gkfs_shell.sfind(...) in test_extended

    ret = gkfs_client.write(file_a, buf, 1)

    assert ret.retval == 1

    preload = 'LIBGKFS_HOSTS_FILE='+str(gkfs_client._patched_env['LIBGKFS_HOSTS_FILE'])+' LD_PRELOAD='+str(gkfs_client._preload_library)

    stream = os.popen(preload+' '+str(gkfs_daemon._workspace.bindirs[1])+'/sfind '+str(topdir)+' -M '+str(gkfs_daemon.mountdir)+' -S 1 -name "*_k*"');

    output = stream.read()

    assert output == "MATCHED 0/4\n"

    cmd = gkfs_shell.sfind(

            topdir,

            f'-M {gkfs_daemon.mountdir}',

            '-S 1',

            '-name "*_k*"'

            )

    assert cmd.exit_code == 0

    assert cmd.stdout.decode() == "MATCHED 0/4\n"

@pytest.mark.skip(reason="invalid errno returned on success")

@pytest.mark.parametrize("directory_path",