[Finder] Fix findertest readability

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | part of #11631, #11588
| License       | MIT

When running on Ubuntu it is hard to setup an account that allows the `chmod` to downgrade the rights on a directory but is not allow to read from the downgraded directory.
parentheses around the assignment can be removed.