fix: RabbitBroker's ping is more objective

[roma-frolov]

Description

I have a situation where RabbitMQ is up, a service is up with a successful connection to RabbitMQ, I stop it, a reconnection occurs to it every n seconds.

in fact there is no connection, my /readiness handle returns 204, although the service is not readiness.

the ping method checks the connection's is_closed flag, although this is not entirely correct, because it will be True only when close/__del__/__aexit__ is called on the connection

checking the connected attribute of the connection object will be more objective: True when there is a connection, False when there is not (there was no connection right away, or a reconnection occurs)

Type of change

• Bug fix (a non-breaking change that resolves an issue)

Checklist

• My code adheres to the style guidelines of this project (scripts/lint.sh shows no errors)
• I have conducted a self-review of my own code
• I have made the necessary changes to the documentation
• My changes do not generate any new warnings
• I have added tests to validate the effectiveness of my fix or the functionality of my new feature
• Both new and existing unit tests pass successfully on my local environment by running scripts/test-cov.sh
• I have ensured that static analysis tests are passing by running scripts/static-analysis.sh
• I have included code examples to illustrate the modifications