Fixed extremely rare race condition in DiscoveryManager

[cmaglie]

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• Tests for the changes have been added (for bug fixes / features)
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• configuration.schema.json updated if new parameters are added.

What kind of change does this PR introduce?

Fix a bug in the discovery manager.

What is the current behavior?

No change

What is the new behavior?

Does this PR introduce a breaking change, and is titled accordingly?

No

Other information

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.50%. Comparing base (2063b6a) to head (092178f).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2589      +/-   ##
==========================================
- Coverage   69.51%   69.50%   -0.01%     
==========================================
  Files         207      207              
  Lines       20280    20285       +5     
==========================================
+ Hits        14097    14099       +2     
- Misses       5069     5071       +2     
- Partials     1114     1115       +1     

Flag	Coverage Δ
unit	69.50% <100.00%> (-0.01%)	⬇️

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