Fixed IBM Waston NLU Credentials toggle link in the ClassifAI setup.

[iamdharmesh]

Description of the Change

As reported in #696, the toggle link for the NLU Credentials toggle link not working in the ClassifAI setup. PR fixes the toggle link and ensures it works properly in the ClassifAI setup.

Closes #696

How to test the Change

1. Go to ClassifAI setup
2. Enable the "Classification" feature in step 1, Click "Start Setup"
3. Navigate to Step 3 (Set up AI Providers)
4. Select (IBM Waston NLU) as a provider
5. Click on Use a username/password instead?/Use an API Key instead? links
6. Verify that the toggle link works properly.

Changelog Entry

Fixed - Ensure that the IBM Watson NLU Credentials toggle link works properly in the ClassifAI setup.

Credits

Props @iamdharmesh

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.