test: do not modify fixtures in test-fs-chmod

`test-fs-chmod` modifies the permissions on files in `test/fixtures`.
This change has the test use the temp directory instead. One of the
fixture files is not used by any other test, so it has been deleted.

I took this opportunity to remove `console.log()` statements from the
test.

PR-URL: https://github.com/nodejs/node/pull/14926


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>