Fix trainer test wrt DeepSpeed + auto_find_bs (#29061)
* FIx trainer test
* Update tests/trainer/test_trainer.py
Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>
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Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>
