Add the rrmSurveyCTA feature flag #13716

Feature Description

The survey CTA express setup for Reader Revenue Manager is built across several issues, and it has to stay hidden from publishers until all of them are complete. This issue adds the rrmSurveyCTA feature flag that the rest of that work is developed behind.

The express setup itself stays behind the existing rrmExpressSetup flag, so that the newsletter sign-up CTA can launch without the survey. The survey setup can only be reached through the express setup, so rrmSurveyCTA only needs to guard the parts that belong to the survey: its registration in the express setup, its entry points, and any survey-specific settings. When rrmExpressSetup is removed at launch, rrmSurveyCTA remains as the only flag for the survey, with nothing to rewire.

For more details, see the Feature flag section of the design doc.

Do not alter or remove anything below. The following sections will be managed by moderators only.

Acceptance criteria

• A new feature flag, rrmSurveyCTA, is added to the list of available feature flags.
• The flag can be turned on and off using the Site Kit Tester Plugin.

Implementation Brief

• Add the rrmSurveyCTA feature flag to the list of feature flags in feature-flags.json.

Test Coverage

• No new tests needed.

QA Brief

• Ensure rrmSurveyCTA feature flag is available in the tester plugin.
• It can be toggled.

Changelog entry

• Add the rrmSurveyCTA feature flag.