[SDK] Fix forceflush may wait for ever #9367

Job	Run time
Bazel asan config	14m 41s
Bazel noexcept	12m 14s
Bazel nortti	12m 30s
Bazel on MacOS	17m 16s
Bazel	12m 21s
Bazel with async export	12m 35s
Bazel tsan config	13m 25s
Bazel valgrind	13m 48s
Bazel with external abseil	12m 8s
Benchmark	7m 58s
CMake test (with abseil)	4m 52s
CMake clang 15 (maintainer mode, abiv2)	13m 54s
CMake clang 15 (maintainer mode, async)	14m 10s
CMake clang 15 (maintainer mode, sync)	13m 57s
CMake do not install test (with otlp-exporter)	13m 57s
CMake gcc 13 (maintainer mode, async)	6m 40s
CMake gcc 13 (maintainer mode, sync)	6m 32s
CMake install test (with abseil)	4m 23s
CMake test (with modern protobuf,grpc and abseil)	18m 19s
CMake msvc (maintainer mode)	7m 6s
CMake msvc (maintainer mode) with C++20	8m 7s
CMake test (with opentracing-shim)	4m 34s
CMake test (build shared libraries with otlp-exporter and static gRPC)	14m 4s
CMake test (with otlp-exporter)	14m 46s
CMake test (without otlp-exporter)	4m 38s
CMake C++14 test(GCC)	4m 18s
CMake C++17 test(GCC)	4m 34s
CMake C++20 test(Clang with libc++)	9m 49s
CMake C++20 test(GCC)	8m 43s
CMake C++23 test(Clang with libc++)	9m 49s
CMake test (without otlp-exporter and with async export)	4m 40s
Code coverage	12m 4s
CMake C++23 test(GCC)	8m 50s
Copyright	5s
DocFX check	52s
Format	18s
markdown-lint	6s
misspell	8s
Plugin -> CMake	1m 5s
CMake -> exporter proto	11m 55s
Bazel Windows	19m 19s
Plugin -> CMake Windows	6m 22s
CMake (With async export) -> exporter proto	11m 52s
CMake -> exporter proto (Build as DLL)	25m 22s
	6h 59m 6s

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