Confluent Kafka: Ensure consume span is ended when consumer is closed

[joshschltelus]

Description

Fix an issue with the confluent kafka instrumentation where the consume span created after a message is received is not closed when the consumer is closed

Type of change

Please delete options that are not relevant.

• [x] Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Added a unit test for close and tested with

tox -e py310-test-instrumentation-confluent-kafka

Does This PR Require a Core Repo Change?

• [x] No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• [x] Followed the style guidelines of this project
• [x] Changelogs have been updated
• [x] Unit tests have been added
• [ ] Documentation has been updated