Bugfix: Addressing OpenTelemetry propagation bug

[WhitWaldo]

Description

Another fix for reported OpenTelemetry issue. The test in #1795 assigned a listener for Dapr.Workflow which showed this as working. By default, .NET returns null silently if there's no activity listener registered for a source meaning the bug persisted when a listener wasn't explicitly registered. Fixed this and added another regression test.

Issue reference

We strive to have all PR being opened based on an issue, where the problem or feature have been discussed prior to implementation.

Please reference the issue this PR will close: #1749

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.42%. Comparing base (85f94fa) to head (26b3595).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1808   +/-   ##
=======================================
  Coverage   65.42%   65.42%           
=======================================
  Files         296      296           
  Lines        8694     8694           
  Branches     1009     1009           
=======================================
  Hits         5688     5688           
  Misses       2761     2761           
  Partials      245      245           

Flag	Coverage Δ
net10.0	65.41% <ø> (ø)

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