Apply small optimization to sharding decode.

[zoj613]

1. This ensures decoding of a shard doesn't fail by ensuring change in array representation due to transposing doesn't cause indexing errors.
2. Empty shard inner chunks don't get created when reading a slice that includes them.

[codecov]

Codecov Report

Attention: Patch coverage is 94.73684% with 1 line in your changes missing coverage. Please review.

Project coverage is 95.00%. Comparing base (aa31327) to head (0c87d7c).

Files	Patch %	Lines
lib/codecs/array_to_bytes.ml	94.73%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #28      +/-   ##
==========================================
+ Coverage   94.82%   95.00%   +0.18%     
==========================================
  Files          13       13              
  Lines        1082     1081       -1     
==========================================
+ Hits         1026     1027       +1     
+ Misses         56       54       -2     

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