Modify deny-listing logic of the Agent

[larohra]

Description

This PR tackles the following -

• Currently the agent blacklists the agent in 3 scenarios. This PR reduces it to a single place
• Add a new flag (reason) in the error.json file to differentiate between new blacklisting logic and old
• Un-blacklist the agents that were blacklisted by the legacy agents in order to clean the state

Issue #

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PR information

• The title of the PR is clear and informative.
• There are a small number of commits, each of which has an informative message. This means that previously merged commits do not appear in the history of the PR. For information on cleaning up the commits in your pull request, see this page.
• If applicable, the PR references the bug/issue that it fixes in the description.
• New Unit tests were added for the changes made

Quality of Code and Contribution Guidelines

• I have read the contribution guidelines.

[codecov]

Codecov Report

Merging #2487 (fc9a985) into develop (b27e475) will decrease coverage by 0.00%.
The diff coverage is 76.74%.

@@             Coverage Diff             @@
##           develop    #2487      +/-   ##
===========================================
- Coverage    72.01%   72.01%   -0.01%     
===========================================
  Files          101      101              
  Lines        15100    15121      +21     
  Branches      2399     2403       +4     
===========================================
+ Hits         10875    10889      +14     
- Misses        3737     3745       +8     
+ Partials       488      487       -1     

Impacted Files	Coverage Δ
azurelinuxagent/ga/update.py	88.56% <76.74%> (-0.48%)	⬇️

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