Support more piece sizes

## Done Criteria
Dealbot does data-storage and retrieval checks with the X piece sizes and annotates the check run accordingly.

### Open Questions
1. What additional piece sizes to use
2. Metric attribute names/values

## Why Important
1. The current 10MB is not fully representative of FOC user experience. Different (and particularly larger) piece sizes demonstrate that an SP can handle such piece sizes and gives a sense of the performance for uploading/downloading at these piece sizes.
2. Ensure SPs aren't just tailoring to the initial simple checks of the dealbot rather than to the wider range of usecases that real users have.

## User/Customer

## Notes