Remove some code in the preview section that isn't needed

[dkotter]

Description of the Change

In #351, a previewer was added to the admin. This makes a request to the Classifier::get_body method, passing in some options. The problem here is that this method expects the options array to look like this:

[
    'text' => 'Some Text'
    'language' => 'en',
    'features' => [
        'categories' => [],
        'concepts' => [],
        // etc
    ],
]

But all we are passing in is a single array containing features part, which looks like:

[
    'categories' => [],
    'concepts' => [],
    // etc
]

These values end up being ignored because they don't follow the format we expect. In addition, these values are the same as the default values in the Classifier::get_body method, so there's no real reason I can see to pass those in the first place. I discovered this while using the preview section to quickly verify a new feature and found out the values I was passing in weren't being recognized.

This PR removes those and also changes the default limit value to match how we set the limit in other places (using our constant first). An alternative approach here is to change the format of the data we pass in to match what we expect but because we just pass in default values, doesn't seem to add any value currently.

How to test the Change

Ensure the preview area still functions as expected

Changelog Entry

Fixed - Removed some unnecessary code in the preview feature

Credits

Props @dkotter

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[jeffpaul]

@dkotter as long as the end result is still "user selects a sample post and can preview the results that Watson returns based on the enabled features & thresholds" then that's fine by me

[dkotter]

@jeffpaul Yeah, this doesn't change any functionality, everything should still work exactly the same. Just removes code that wasn't actually being used because it was in the wrong format. Could fix the format so it is used but since it's exactly the same as the default data, seemed better to just remove it.

[jeffpaul]

@Sidsector9 would be great to wrap up review here so this can get merged before end of month when I'd like to get out the next major release

[Sidsector9]

Approving as the tests are failing not because of the changes in this PR.