Remove `group_ip_restrictions_allow_global` feature flag

Remove the group_ip_restrictions_allow_global feature flag

See Free users with service ping data sharing enabl... (#364630 - closed) and refer to @robotmay_gitlab for more context.

Testing

Please run package-and-qa in the MR for regression purposes

Feature flag cleanup

If not already done, clean up the feature flag from all environments by running these chatops command in #production channel:

• /chatops run feature delete group_ip_restrictions_allow_global --dev
• /chatops run feature delete group_ip_restrictions_allow_global --staging
• /chatops run feature delete group_ip_restrictions_allow_global