Fix SendRequestAsync hang on Streamable HTTP SSE retry #2358

Job	Run time
build (macos-latest, Release)	6h 5m 0s
build (macos-latest, Debug)	5m 15s
build (windows-latest, Debug)	13m 18s
build (ubuntu-latest, Release)	13m 39s
build (ubuntu-latest, Debug)	12m 48s
build (windows-latest, Release)	9m 28s
publish-coverage	0s
	6h 59m 28s

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