fix: multiple pagers with models do not work

[kenjis]

Description
Fixes #6204

I am not sure if there is something wrong with sharing Pager.
But without sharing the Pager, multiple pagers never work.

See https://codeigniter4.github.io/CodeIgniter4/libraries/pagination.html#paginating-multiple-results

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[iRedds]

Can you add tests for this case?

[kenjis]

Yes, I will add test later.

[MGatner]

I don't really understand how or why one would "multiple paginate" but it does seem that with grouping we would need the shared Pagination instance. Test verified this.

One suggestion to make the comparison explicit.