Y24-375 - File downloads improvements for MVP

[KatyTaylor]

User story
Tweaks to get these file downloads ready for the MVP version.

Who are the primary contacts for this story
Abby, Katy

Who is the nominated tester for UAT
Abby

Acceptance criteria
To be considered successful the solution must allow:

• Refactor storage of common constants in the following 3 files so that they are not duplicated: hamilton_lrc_pbmc_defrost_pbs_to_lrc_pbmc_pools, hamilton_lrc_pbmc_defrost_pbs_to_cellaca_count, hamilton_gem_x_5p_chip_loading
• Why are there two constants, required_number_of_cells and default_required_number_of_cells in the scrna_core_dna_prep.yml config? Are they the same thing?
• For the chip loading file, hamilton_gem_x_5p_chip_loading, the value for the number of cells on the chip well (90,000) is not hardcoded, but is drawn from the request metadata (value has to be saved when pooling is done).

Dependencies

• Have to decide how the value for the number of cells on the chip well will be stored. It will be saved in another story (yet to be created), to do with the pooling algorithm. It may not be the same as the value that is originally requested in the submission.

References
Following on from:

• Y24-319 - Pooling driver file tweaks #1914
• Y24-321 - Cell counting driver file for pools plate #1915
• Y24-193 - Add volume columns to the driver file for PBMC Pools to GEM-X 5p Chip #1779