* [Fix] Call SyncBufferHook before validation in IterBasedTrainLoop

* Add before_val_epoch in SyncBuffersHook

* Fix white space format

* Add comments for SyncBuffersHook

* Add comments for SyncBuffersHook

Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

* Add comments for SyncBuffersHook

Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

* Fix white space format

* Add before_test_epoch

* Remove before_test_epoch

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Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>