Convert activation key upgrade scenario to new format

[synkd]

Problem Statement

The activation key upgrade scenario is currently failing and uses the old upgrade test format.

Solution

Convert the test to the new format using the shared_resource framework and converting the pre-upgrade test to a pytest fixture.

Remove entitlement-related steps as entitlement mode has been removed from Satellite 6.16+.

Related Issues

This test currently fails on the final org.delete() step due to SAT-28990.