Default Product Analytics Admin Settings

What does this MR do and why?

This MR default enables product_analytics_admin_settings feature flag. The feature flag will be cleaned up in 17.0.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

FF state	Screenshot
Enabled
Doesn't exist
Disabled

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Set up product analytics
2. Remove the feature flag record if you have any

 Feature.remove(:product_analytics_admin_settings)

1. You should still be able to see product analytics settings at the admin settings (http://gdk.test:3000/admin/application_settings/general).
2. Disable the feature flag record

 Feature.disabled(:product_analytics_admin_settings)

1. You should not see the product analytics settings in admin settings (http://gdk.test:3000/admin/application_settings/general).

Related to #385602 (closed)