Update agent integration tests

[vepatel]

• https://github.com/nginx/kubernetes-ingress/blob/main/tests/suite/test_app_protect_agent.py
• https://github.com/nginx/kubernetes-ingress/blob/main/tests/suite/test_agent.py

current agent python tests only verify if the agent is installed using -v commands. I'd like to update the tests to check the nginx-agent.conf file in the pod and make sure the it is correct i.e. reflects the parameters passed through agent configmap

[github-actions]

Hi @vepatel thanks for reporting!

Be sure to check out the docs and the Contributing Guidelines while you wait for a human to take a look at this 🙂

Cheers!