[GraphBolt] enable `OnDiskFeature` with io_uring for RGCN+ogbn-mag240m example

[Rhett-Ying]

🔨Work Item

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

Description

OnDiskFeature is enabled in https://github.com/dmlc/dgl/pull/7128.

Try with RGCN + ogbn-mag240m: https://github.com/dmlc/dgl/tree/master/examples/sampling/graphbolt/rgcn#run-on-ogb-lsc-mag240m-dataset

Depending work items or issues