Fixed generation of performance test endpoints for Nautobot apps.

[HanlinMiao]

Closes #6858

What's Changed

Instead of taking an "educated guess" of the nautobot app base_url, I refactored the command to take the base_url directly from the installed apps' respective AppConfig.

We do have unit tests in place to test all the generated endpoints, I included some of the apps seen on demo.nautobot.com to show the mechanism is working correctly.
I will remove them from pyproject.toml and poetry.lock if the PR is approved

Screenshots

N/A

TODO

• Explanation of Change(s)
• Added change log fragment(s) (for more information see the documentation)
• Attached Screenshots, Payload Example
• Unit, Integration Tests
• Documentation Updates (when adding/changing features)
• Example App Updates (when adding/changing features)
• Outline Remaining Work, Constraints from Design