[BUGFIX] WAR the dataloader issue with forked processes holding stale references

[ptrendx]

Description

See #19918 (comment) for the explanation of the issue and the WAR.

@szha

Checklist

Essentials

• PR's title starts with a category (e.g. [BUGFIX], [MODEL], [TUTORIAL], [FEATURE], [DOC], etc)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage
• Code is well-documented

[mxnet-bot]

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