[5.x] update zarr test data

[haileyajohnson]

Description of Changes

• reduce number of files (chunks) in test data set
• add extra test cases (nested array, uninitialized array, partially initialized array, etc.)
• remove compressor from current test data (compression to be tested separately)

PR Checklist

• Indicate the version associated with this PR in the Title
  (e.g. "[5.x]: This is my PR title")
• Link to any issues that the PR addresses
• Add labels, especially if the PR should be ported to other versions
  (these labels start with "port: ")
• Open as a draft PR
  until ready for review
• Make sure GitHub tests pass
• Mark PR as "Ready for Review"

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This change is 

[lesserwhirls]

Looks good!

Reviewed 1053 of 1053 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @dopplershift)