increasing memory consumption when using object_randomization

[rojas70]

In picking.py,
When the self.object_randomization flag is set to True, _reset_internal() also activate the self.hard_reset flag on.

The flag is used in environments/base.py:reset().
When self.hard_reset is on, the following code is called starting on L311:

        if self.hard_reset and not self.deterministic_reset: #TODO: investigate increasing memory consumption when calling this every rollout
            self._destroy_viewer()
            self._load_model()              #  Create a manipulation task objec (arena/robot/object/placement of objects/goal objects)
            self._postprocess_model()
            self._initialize_sim()

When this is called at the end of every rollout, our memory usage increases significantly over the lifetime of the experiment, always resulting in an out of RAM segfault.

If we only randomize every 200 epochs we see this stabilizes, but we have not figured out the underlying cause.

[rojas70]

By only doing hard resets when ALL objects are picked up and not every reset, this number seems stable... will keep monitoring