[INSTA-3039] Ensure locally executable UT

[CagriYonca]

This PR consists of two commits:

• Improved confluent-kafka's global context variable.
• Improved docker-compose file to integrate unittests.

You can run infra as before using this command:

• docker compose --profile infra-general up -d

Unittests in the docker-compose file currently supports up to Python version 3.14.

Run tests for all Python versions:

• docker compose --profile infra-general --profile tests-general up --build --abort-on-container-exit | grep python-sensor-test

To run tests for a specific Python version using Docker, 3.12 for example:

• docker compose --profile infra-general --profile py312 up --build --abort-on-container-exit | grep python-sensor-test

Cassandra Tests:

• docker compose --profile infra-cassandra --profile tests-cassandra up --build --abort-on-container-exit | grep python-sensor-test

Kafka Tests:

• docker compose --profile infra-kafka --profile tests-kafka up --build --abort-on-container-exit | grep python-sensor-test

Gevent Tests:

• docker compose --profile tests-gevent up --build --abort-on-container-exit | grep python-sensor-test

AWS Tests:

• docker compose --profile tests-aws up --build --abort-on-container-exit | grep python-sensor-test