[Release-3.14.1][Bug] Fix cfn-hup endless loop after rollback to cluster state older than 24 hours

[hehe7318]

Description of changes

When a cluster update fails and triggers a rollback to a state older than 24 hours, cfn-hup enters an endless loop on the head node. This happens because:

1. The rollback restores the launch template metadata to reference an expired wait condition handle (wait conditions expire after 24h)
2. cfn-signal fails to signal the expired handle and returns non-zero
3. cfn-hup sees the non-zero exit code and does not update its local metadata cache (metadata_db.json)
4. On the next polling interval, cfn-hup detects the same "change" and re-triggers the update recipe, creating an infinite loop

This fix appends || exit 0 to the update command, ensuring cfn-hup always updates its metadata cache regardless of whether cfn-signal succeeds or fails. This prevents the endless loop while still allowing CloudFormation to handle timeouts appropriately.

Tests

• TODO: manually test.
• TODO: integ test.

Checklist

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• Check if documentation is impacted by this change.

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