Cleanup ResilienceStrategyBuilder

[martintmk]

Details on the issue fix or feature implementation

Follow-up of #1236. I realized we can drop some more unnecessary duplications in each builder by leveraging extension methods for basic scenarios.

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 #1240 (855b005) into main (045cec0) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1240      +/-   ##
==========================================
- Coverage   82.81%   82.79%   -0.02%     
==========================================
  Files         263      264       +1     
  Lines        6103     6096       -7     
  Branches      966      966              
==========================================
- Hits         5054     5047       -7     
  Misses        844      844              
  Partials      205      205              

Flag	Coverage Δ
linux	82.79% <100.00%> (-0.02%)	⬇️
macos	82.79% <100.00%> (-0.02%)	⬇️
windows	82.79% <100.00%> (-0.02%)	⬇️

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Impacted Files	Coverage Δ
...rc/Polly.Core/ResilienceStrategyBuilder.TResult.cs	100.00% <ø> (ø)
src/Polly.Core/ResilienceStrategyBuilder.cs	100.00% <ø> (ø)
...lly.Core/Strategy/ResilienceStrategyBuilderBase.cs	100.00% <ø> (ø)
...ack/FallbackResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)
...ging/HedgingResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)
.../Polly.Core/ResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)