Fix OnHedging not being called

[martintmk]

Details on the issue fix or feature implementation

The OnHedging callback was not called when the outcome is not available due to the callback taking too long.

Confirm the following

• I started this PR by branching from the head of the default branch
• I have targeted the PR to merge into the default branch
• I have included unit tests for the issue/feature
• I have successfully run a local build

[codecov]

Codecov Report

Merging #1320 (907bde2) into main (ce97ea5) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1320      +/-   ##
==========================================
+ Coverage   83.37%   83.42%   +0.04%     
==========================================
  Files         268      268              
  Lines        6335     6352      +17     
  Branches     1001     1001              
==========================================
+ Hits         5282     5299      +17     
  Misses        844      844              
  Partials      209      209              

Flag	Coverage Δ
linux	?
macos	83.42% <100.00%> (+0.04%)	⬆️
windows	83.42% <100.00%> (+0.04%)	⬆️

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Impacted Files	Coverage Δ
...lly.Core/Hedging/HedgingStrategyOptions.TResult.cs	100.00% <ø> (ø)
...rc/Polly.Core/Hedging/HedgingResilienceStrategy.cs	100.00% <100.00%> (ø)
src/Polly.Core/Hedging/OnHedgingArguments.cs	100.00% <100.00%> (ø)