Commit 65986b8e flipped the iso_hfs_ppc64le_compatible default from True
to False but the createiso phase tests still asserted hfs_compat=True for
the cases that rely on the default. Update the four affected expectations
so test_start_one_worker, test_bootable, and test_bootable_but_failed
pass again. The test that explicitly sets the option (already False) is
unchanged.
