Update collections tutorial to meet GTN stylistic standards

https://training.galaxyproject.org/training-material/topics/galaxy-interface/tutorials/collections/tutorial.html#processing-data-organized-as-a-collection needs to be updated, there are a few low hanging fruit for anyone wanting to help!

- Hands on activities need to be in hands on boxes (from linked section)
- They need to use the standard layout for "import data" that is used across tutorials
- Remove videos
- Remove screenshots
- Remove "Click execute"
- Improve figure captions which are not sufficient for a visually impaired user. [what's appropriate for alt-text vs captions in the GTN Contributing Guide](https://training.galaxyproject.org/training-material/topics/contributing/tutorials/create-new-tutorial-content/tutorial.html#guidelines-on-alt-vs-figcaption-text)
- Fix rST style image (`.. image:: ${static_path}/images/tools/collection_ops/filter_empty.svg :width: 500 :alt: Filtering empty datasets`)
- Fix tool references to use modern GTN tool referencing [guide on how to do it](https://training.galaxyproject.org/training-material/topics/contributing/tutorials/create-new-tutorial-content/tutorial.html#tool-links)