Bump default Agent version to 7.55.2 (#1332)

[levan-m]

What does this PR do?

cherry-pick #1332

Motivation

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Additional Notes

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Minimum Agent Versions

Are there minimum versions of the Datadog Agent and/or Cluster Agent required?

• Agent: vX.Y.Z
• Cluster Agent: vX.Y.Z

Describe your test plan

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Checklist

• PR has at least one valid label: bug, enhancement, refactoring, documentation, tooling, and/or dependencies
• PR has a milestone or the qa/skip-qa label

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 55.24%. Comparing base (f452dac) to head (4d11db8).

Additional details and impacted files

@@           Coverage Diff           @@
##             v1.8    #1346   +/-   ##
=======================================
  Coverage   55.24%   55.24%           
=======================================
  Files         247      247           
  Lines       28403    28403           
=======================================
  Hits        15690    15690           
  Misses      11829    11829           
  Partials      884      884           

Flag	Coverage Δ
unittests	55.24% <ø> (ø)

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Files	Coverage Δ
pkg/defaulting/images.go	100.00% <ø> (ø)

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