Add build string to packages in conda environment files

[bnemanich]

Checklist before submitting

• Did you read the contributor guide?
• Did you update any affected documentation?
• Did you write any tests to validate this change?

Description

The pyarrow package doesn't have meta packages with different names for choosing cpu and cuda builds. Instead, it relies on the information in the build string for picking the correct package. Because of this, the conda environment files that we are currently generating always pick the default build type.

This PR adds the build strings to the generated packages listed in the conda environment files, which will allow for the correct version of pyarrow to be selected.

Review process to land

1. All tests and other checks must succeed.
2. At least one maintainer must review and approve.
3. If any maintainer requests changes, they must be addressed.

[codecov-commenter]

Codecov Report

Merging #36 (701499a) into main (0a67c27) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #36      +/-   ##
==========================================
+ Coverage   95.51%   95.52%   +0.01%     
==========================================
  Files          21       21              
  Lines        1847     1851       +4     
==========================================
+ Hits         1764     1768       +4     
  Misses         83       83              

Flag	Coverage Δ
unittests	95.52% <100.00%> (+0.01%)	⬆️

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Impacted Files	Coverage Δ
open_ce/build_tree.py	92.71% <100.00%> (+0.02%)	⬆️
open_ce/conda_utils.py	98.65% <100.00%> (+0.06%)	⬆️

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