fix: make "Secret in Secrets Manager" more consistent

[agateau-gg]

Context

In ggshield text output, the value for the "Known by GitGuardian dashboard" is "YES" or "NO", but the value for the new "Secret in Secrets Manager" is "true" or "false".

What has been done

This commit makes "Secret in Secrets Manager" use "YES" or "NO" too.

Before:

>> Secret detected: Generic Password
   Validity: No Checker
   Occurrences: 1
   Known by GitGuardian dashboard: NO
   Incident URL: N/A
   Secret SHA: bcab461d00a692b05add54f547d83660290e1a22504db841d7a9c325451bf20b
   Secret in Secrets Manager: False
   Detector documentation: https://docs.gitguardian.com/secrets-detection/secrets-detection-engine/detectors/generics/generic_password

After:

>> Secret detected: Generic Password
   Validity: No Checker
   Occurrences: 1
   Known by GitGuardian dashboard: NO
   Incident URL: N/A
   Secret SHA: bcab461d00a692b05add54f547d83660290e1a22504db841d7a9c325451bf20b
   Secret in Secrets Manager: NO
   Detector documentation: https://docs.gitguardian.com/secrets-detection/secrets-detection-engine/detectors/generics/generic_password

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.91%. Comparing base (9a6a393) to head (538facf).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1102   +/-   ##
=======================================
  Coverage   91.90%   91.91%           
=======================================
  Files         144      144           
  Lines        6091     6094    +3     
=======================================
+ Hits         5598     5601    +3     
  Misses        493      493           

Flag	Coverage Δ
unittests	91.91% <100.00%> (+<0.01%)	⬆️

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