Append prioritized label before pagination

What does this MR do?

Previously, when label's priority was toggled, we used to find the .label-list-item container and append the detached label there. This had an innate flaw of appending after the Pagination component.

With this, we find the last .label-list-item in the target label container and append after that label item.

What are the relevant issue numbers?

#24875 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer

Closes #24875 (closed)