Move the '✅️ PHPStan Tests' job to the lint section

Problem/Motivation

Follow-up of #3464978: Make PHPStan rule testing use PHPUnit 10.

it would make sense to move the '✅️ PHPStan Tests' job from the db-dependent tests into the lint section of .gitlab-ci.yml

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet