Update DiagnosticSource to 4.4 stable.

[cijothomas]

SDK version updated to 2.4.0
Update changelog

[codecov-io]

Codecov Report

Merging #574 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #574   +/-   ##
========================================
  Coverage    84.01%   84.01%           
========================================
  Files          137      137           
  Lines         6088     6088           
  Branches       874      874           
========================================
  Hits          5115     5115           
  Misses         644      644           
  Partials       329      329

Impacted Files	Coverage Δ
...annel/Shared/Implementation/TransmissionStorage.cs	90.57% <0%> (-1.45%)	⬇️
...Core/Managed/Shared/Extensibility/MetricManager.cs	70.37% <0%> (+1.23%)	⬆️
...metryChannel/Shared/Implementation/PlatformFile.cs	95.65% <0%> (+4.34%)	⬆️

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