Fix channel handling for RabbitMQ driver, mock Partition in int tests

Description:

Connection issue:
The RabbitMQ Driver was handling connections to RabbitMQ in an inappropriate way, creating an excessive amount of connections.
Fix:
Publisher and consumer connection handlers were added, to share a connection.

Redundant integration with Partition service in int tests:
Integration tests required up and running Partition service, making overall testing more complex.
Fix:
Partition integration was mocked, but original driver builders are still used, to verify their complex functionality.

How to test:

Does functionality was tested and how?

Changes include:

• Refactor (a non-breaking change that improves code maintainability).
• Bugfix (a non-breaking change that solves an issue).
• New feature (a non-breaking change that adds functionality).
• Breaking change (a change that is not backward-compatible and/or changes current functionality).

Changes in:

• GC
• Azure
• AWS
• IBM

Dev Checklist:

• Added Unit Tests, wherever applicable.
• Updated the Readme, if applicable.
• Existing Tests pass
• Verified functionality locally
• Self Reviewed my code for formatting and complex business logic.