Release Post 14.7 Correction: Correct personalization questions upon group creation customization to Self-Managed only

The 14.7 release post incorrectly indicates a new setting to enable/disable personalization questions during group creation as SaaS-supported. This is an admin-panel feature that is only accessible at current time to self-managed instances.

Docs correctly state Self-Managed only: https://docs.gitlab.com/ee/user/admin_area/settings/third_party_offers.html