Matching log-source tagging for diagnosability with previous apt changes

[kjohn-msft]

This PR makes no functional changes to the code beyond:

• more clarity in logging origin through tagging with source file acronyms.
• deprioritizing some logs (debug to verbose) that are in years-old highly stable code paths.

This is similar to code that's already gone in for Apt.

[codecov]

Codecov Report

Attention: Patch coverage is 82.82828% with 34 lines in your changes missing coverage. Please review.

Project coverage is 92.22%. Comparing base (772ba51) to head (4d45494).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/core/src/package_managers/YumPackageManager.py	84.00%	16 Missing ⚠️
.../core/src/package_managers/ZypperPackageManager.py	83.13%	14 Missing ⚠️
src/core/src/package_managers/PackageManager.py	71.42%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #282      +/-   ##
==========================================
- Coverage   92.23%   92.22%   -0.01%     
==========================================
  Files          92       92              
  Lines       16035    16017      -18     
==========================================
- Hits        14790    14772      -18     
  Misses       1245     1245              

Flag	Coverage Δ
python27	92.22% <82.82%> (-0.01%)	⬇️
python39	92.22% <82.82%> (-0.01%)	⬇️

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