Small fixes for the audio classifier agent

[codingbandit]

Small fixes for the audio classifier agent

Details on the issue fix or feature implementation

Fixes the reference key in the exploded objects collection, fixes file upload for non-OpenAI.Assistants agents.

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• [x] I started this PR by branching from the head of the default branch
• [x] I have targeted the PR to merge into the default branch
• [x] This PR needs to be cherry-picked into at least one release branch
• [ ] I have included unit tests for the issue/feature
• [ ] I have included inline docs for my changes, where applicable
• [x] I have successfully run a local build
• [ ] I have provided the required update scripts, where applicable
• [ ] I have updated relevant docs, where applicable