[PP-1] Remove workaround added for AJAX pager

Problem/Motivation

In 📌 Refactor translation UI/form Active , we had to add an override for the pager initialization because the pager ID was changed for the first time the (AJAX) pager was used; so the content wasn't updated. (This happened only for the first paging action, every other paging is successful).

The scope of this ticket is to remove / adjust this workaround when the corresponding core issue 🐛 Ajax callbacks on paginated forms with PagerSelectExtender not updating on first callback Active is resolved.

Steps to reproduce

1. Install Drupal and Babel
2. Add a language
3. Remove these lines from Babel's code: https://git.drupalcode.org/project/babel/-/blob/18750667a0ff003fa6b2698c...
4. Try to use pagination on the Babel translate form (will break both with and without JavaScript).

Proposed resolution

After the core issue is resolved, repeat the steps at Steps to reproduce.
Pager should work correctly (JS and non-JS).

Remaining tasks

User interface changes

Nothing

API changes

Nothing

Data model changes

Nothing