[REVIEW] ENH gpuCI Script Updates

[dillon-cullinan]

Overview
First step before "Project Flash" to improve gpuCI scripts and allow for use of different node types for CPU builds. Post "Project Flash" there will be another round of improvements and updates with the goal to make these scripts easier to maintain.

Changes

• Consolidates some of the CPU gpuCI scripts, reducing number of scripts to maintain
• Standardizes naming of the upload script to upload.sh
• Changes logging to use gpuci_logger where practical
• Updates comments and documentation where necessary
• Enables gpuCI to override environment variables based on node types

[GPUtester]

Please update the changelog in order to start CI tests.

View the gpuCI docs here.

[codecov-io]

Codecov Report

Merging #3010 into branch-0.16 will decrease coverage by 0.03%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           branch-0.16    #3010      +/-   ##
===============================================
- Coverage        68.65%   68.62%   -0.04%     
===============================================
  Files              235      235              
  Lines            18539    18539              
===============================================
- Hits             12728    12722       -6     
- Misses            5811     5817       +6     

Impacted Files	Coverage Δ
python/cuml/test/conftest.py	61.20% <0.00%> (-5.18%)	⬇️

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