Consider small fastq files

[Stephanie Spielman]

Related to #101
Rather than only paying attention to timing of the FASTQ activity, we can also use different FASTQ files that are smaller in the first place. One approach for this could be to simply subset the FASTQs we've identified and keep those in an S3 bucket on our end. During training, we'd want to explain to participants that:

• They can still curl from SRA! We'll want to show them the link and command to do so.
• The only reason we using a subsetted version in our AWS data storage is for timing needs during training. Internet speed is unreliable!