Cancel main task in aclose

[martin-purplefish]

Also simplified a few places in the main loop code - no other functional changes.

This wasn't really a big deal, since the job logic would clean it up anyway. But if someone was using it outside of a job, it'd run forever.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 3f1a0c40f95c06c03f290f6d3c89956f811bbbe1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
livekit-agents	Patch

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[martin-purplefish]

PTAL @theomonnom