Fix Replace in... unit tests

This addresses [this comment](https://github.com/adobe/brackets/pull/8029/files#r13728201).

1. In both tests, I forgot to pass the `dirEntry` as the first param to the `openSearchBar()` function.

2. After doing that, I discovered that that the path was wrong

3. In the second test, should have created a `fileEntry`.

cc @njx