Inconsistent ServiceBusClient lifecycle management #4977

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Describe the bug
key message listeners repeatedly instantiate ServiceBusClient inside infinite loops but discard the instances without calling close() or wrapping them in context managers. This can leak connection sockets and AMQP channels under transient reconnect loops.

Steps to reproduce

1. this might be difficult to observe as it could take a while for enough sockets to be leaked

Azure TRE release version (e.g. v0.14.0 or main):
main
Deployed Azure TRE components - click the (i) in the UI:
latest