Port remaining dataset tests to new architecture

[pmeier]

🚀 Feature

Port remaining dataset tests to new architecture.

Motivation

#3402 added new infrastructure for dataset tests. In a number of follow-up PRs tests for datasets were added that previously weren't tested. The following datasets still use the old test architecture:

• ImageNet
• WIDERFace
• CityScapes
• SVHN
• Places365
• STL10

Pitch

Port the remaining dataset tests to the new architecture.

cc @pmeier

[prabhat00155]

All the aforementioned tests have been ported to the new test framework.