Fix CustomProgressBar for resume
# What does this PR do ?

- Fix the CustomProgressBar for cases when we are resuming training from a checkpoint. Currently when we are resuming from a checkpoint total value in `iter_num/total` of the progress bar is the number of remaining training steps instead of total training steps which leads to the progress bar displaying` iter_num/?` when iter_num > remaining training steps. This PR fixes the issue by reseting the total with `max_steps`.
- Also, in case of multiple epochs the PR updates the current step number (n) to be the current step number within an epoch (default was current step across an epoch and this can lead to an errored progress bar).

**Collection**: [Note which collection this PR will affect]

# Changelog 
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# Usage
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```python
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- [ ] Bugfix
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# Additional Information
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