directory seek test: code does not agree with comment. Fix code.

the directory was opened with the seek right, and this test says that it
was asserting that the seek right was present. However, the test was
actually asserting that the seek right was *not* present.

This fixes the code of the test, because I believe the comment is
correct.

crates/wasi-c2/TEST_FAILURES

@@ -16,9 +16,6 @@ wasi_tests::remove_directory_trailing_slashes
     - cap-std Dir::remove_dir gives EINVAL when trying to remove dir with
       trailing slash. otherwise, everything passes.
 
-wasi_tests::directory_seek
-    - something weird about directory open rights / fdstat. need debug
-      impl of Caps to see about this
 wasi_tests::fd_flags_set
     - set_fdflags is not implemented. test wanted to clear O_APPEND mode
 wasi_tests::path_filestat