Fix: custom DelegatingHandler does not run again on each retry with AddStandardResilienceHandler
A DelegatingHandler registered before AddStandardResilienceHandler runs once per logical request, not once per retry. Move it after the resilience handler, and make it idempotent, because the retry re-sends the same HttpRequestMessage. Measured on Microsoft.Extensions.Http.Resilience 10.10.0 and 8.10.0.