DM-4340: Don't render RECAPTCHA if key isn't available

[camillevilla]

JIRA issue link

DM-4340

Description - what does this code do?

• small follow up to DM-4340 to get tests that involve email forms passing. This only affects local dev and testing.

Testing done - how did you test it/steps on how can another person can test it

1. Make sure that RECAPTCHA_SITE_KEY_V3 is not present in your local .env file.
2. On master, start local dev and navigate to About.
3. You should receive the error Recaptcha::RecaptchaError in About#index No site key specified.
4. Check out this branch. Restart your server and navigate to the About page. The form should still render. Check the inspector and confirm that no recaptcha snippet is loaded.

[camillevilla]

Closing this PR since we'll be removing the relevant form.