Add iteration time test as part of regression testing

[karan6181]

Description of changes:

• Add iteration time test as part of regression testing

Issue #, if available:

STR-89

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[b-chu]

It seems like the PR includes a refactor and a new regression test. Can you write a description of what you're refactoring (longer) and what iteration time is testing (shorter)?

Also would it be better to separate out this PR into 3 PRs? One for refactor, one for the new datasets, and one for the time test?

[b-chu]

Was there something that changed the dataloader to return dictionaries of lists in a batch instead of dictionaries of tensors?