Remove feature flag for create package service

What does this MR do and why?

Refactor create package services (!201306 - merged) refactored the create package service to use a package class instead of a package type with the feature flag.

The feature flag was globally enabled on gitlab.com on 2025-08-25 link

This MR remove the feature flag from create package service.

References

Foundation: Prepare application code to read fr... (#548761 - closed)

Screenshots or screen recordings

No.

How to set up and validate locally

The validation of the changes is identical to the validation when the refactoring was introduced and described here.

MR acceptance checklist

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Related to #548761 (closed)