Skip deleting nodes during batch sessions

We recently made it so that arnold nodes are deleted as soon as they need to, but this might not be a good thing to do in batch sessions. For procedural child nodes, we can get warnings saying that we're "deleting a node during update with a batch session", which is not allowed. In that case we should give the node an empty name (so that a new node can be created with that same name again), and call `AiNodeSetDisable` on it.

We might even want to extend that change to renders without a procedural parent. At the moment, when we render e.g. with husk, at the end we delete all the nodes one by one as the hydra primitives are being deleted. But in a batch session, this could probably be skipped, and therefore let arnold destroy the universe in a more optimized way

No files, tests, or entry points are named. Start by locating the batch-session handling for procedural child nodes and the end-of-render Hydra primitive cleanup, then verify the behavior for empty-name disabled nodes and confirm that batch sessions finish without deletion warnings.

Written by the indexing model from the issue text.