Add gitlab-qa scenario to test upgrades of AI components

As noted in Improve Test Coverage for Self Managed AI Upgrades (gitlab-org/quality&82) we have identified a potential maintenancetest-gap in the area of upgrades for self managed customers in the context of AI related infrastructure.

A proposed solution is to create a scenario that merges concepts from the AI Gateway Scenarios and the UpdateFromPrevious so that we will be in a position to verify that self managed customers can run upgrades from their instances, and ensure that these upgrades remain compatible with GitLab managed services that gate access to AI related features.