Remove feature flag for packages tags finder

What does this MR do and why?

Refactor packages tags finder to use packages c... (!199578 - merged) implemented the refactoring to the packages tags finder with the feature flag.

The feature flag was gradually rolled out and successfully enabled on gitlab.com #557895 (comment 2692461579).

This MR remove for the packages tags finder to use always a package class instead of a package type.

References

Screenshots or screen recordings

No.

How to set up and validate locally

1. Publish npm package

   $ mkdir madrid && cd madrid
   $ npm init
   # Set package name according [the naming convention](https://docs.gitlab.com/user/packages/npm_registry/#naming-convention).
   # Setup [authentication](https://docs.gitlab.com/user/packages/npm_registry/#authenticate-to-the-package-registry)
   $ npm publish

2. Add a new tag to npm package docs

   $ npm dist-tag add @scope/package@version my-tag
   $ npm dist-tag ls @scope/package # verify that the tag was added

3. Remove a tag from npm package docs

   $ npm dist-tag rm @scope/package@version my-tag
   $ npm dist-tag ls @scope/package # verify that the tag was removed

MR acceptance checklist

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

Related to #548761 (closed)