[SDK] Fix deadlock when shuting down http client #8566

Job	Run time
Bazel noexcept	19m 10s
Bazel nortti	18m 20s
Bazel asan config	13m 21s
Bazel on MacOS	20m 27s
Bazel	21m 10s
Bazel with async export	20m 4s
Bazel tsan config	21m 43s
Bazel valgrind	28m 17s
Bazel with external abseil	24m 8s
Benchmark	17m 42s
CMake test (with abseil)	6m 46s
CMake clang 14 (maintainer mode, async)	20m 28s
CMake clang 14 (maintainer mode, sync)	25m 30s
CMake do not install test (with otlp-exporter)	20m 46s
CMake gcc 4.8 (with otlp exporter)	13m 40s
CMake gcc 4.8 (without otlp exporter)	5m 53s
CMake gcc 12 (maintainer mode, async)	12m 46s
CMake gcc 12 (maintainer mode, C++11, async)	14m 45s
CMake gcc 12 (maintainer mode, sync)	11m 28s
CMake install test (with abseil)	6m 4s
CMake test (with modern protobuf,grpc and abseil)	32m 40s
CMake msvc (maintainer mode)	12m 10s
CMake test (with opentracing-shim)	7m 41s
CMake test (build shared libraries with otlp-exporter and static gRPC)	20m 0s
CMake test (with otlp-exporter)	21m 8s
CMake test (without otlp-exporter)	6m 50s
CMake C++20 test(Clang with libc++)	11m 1s
CMake C++20 test(GCC)	12m 54s
CMake test (without otlp-exporter and with async export)	6m 29s
Code coverage	13m 54s
Copyright	10s
DocFX check	2m 1s
Format	18s
markdown-lint	8s
misspell	7s
Plugin -> CMake	1m 20s
CMake -> exporter proto	21m 51s
Bazel Windows	35m 39s
Plugin -> CMake Windows	10m 30s
CMake (With async export) -> exporter proto	18m 26s
CMake -> exporter proto (Build as DLL)	19m 46s
	9h 57m 31s

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