[GraphBolt] Default value of `persistent_workers` should be `False`

[Rhett-Ying]

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Project tracker: https://github.com/orgs/dmlc/projects/2

Description

As gb.DataLoader inherits from torch.utils.data.DataLoader(https://pytorch.org/docs/stable/data.html#torch.utils.data.DataLoader), the default value of persistent_workers should be same. But for now, we're using True while torch uses False.

Depending work items or issues

[frozenbugs]

https://github.com/dmlc/dgl/blob/41a38486a5ed9298093d9f0bc415751269c7d577/python/dgl/graphbolt/dataloader.py#L58