fix(recaptcha): remove v3 from heading; preserve settings on toggle

[dkoo]

All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Fixes the heading for reCAPTCHA in Newspack > Settings, and fixes a small bug when toggling on or off.

How to test the changes in this Pull Request:

1. On epic/ia, visit Newspack > Settings.
2. Observe that the reCAPTCHA settings heading says reCAPTCHA v3.
3. Toggle on reCAPTCHA, select v2, enter some credentials, and save.
4. Toggle off reCAPTCHA, then toggle on again, and observe that the settings you saved in step 3 have been lost.
5. Check out this branch and refresh.
6. Confirm that the heading now says just reCAPTCHA.
7. Repeat steps 3-4 and confirm that after toggling reCAPTCHA on again, your previously saved settings are restored.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?