Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/9791200

    * fix trainer about iters_per_epoch

Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/9660779

    * fix unittest

1. Support `ReduceLROnPlateau` lr scheduler, and add  `PlateauLrSchedulerHook` for it
2. Support custom `optimizer_hook` and `lr_scheduler_hook`
3. Remove function of save best ckpt from `EvaluationHook`, replace with `BestCkptSaverHook`
4. `evaluation_loop` return metric values directly，move metric computation to `single_gpu_test` and `multi_gpu_test`
        Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/9584322

    * [to #43627720] support ReduceLROnPlateau and fix lr scheduler

Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/9551089

    * support distributed training