QueryPipeline incremental update from physics_pipeline doesn't update removed colliders

[Ughuuu]

When calling physics_pipeline.step, it calls automatically QueryPipeline.update_incremental but gives param refit_and_rebalance to false. If someone doesn't call again QueryPipeline.update then the QueryPipeline.qbvh will keep growing forever (because nodes are marked as dirty but aren't actually removed.

[finnbear]

This might relate to #617 (although, at the time of writing, I thought refit_and_rebalance was true at least once per step)