[BUILD] Fix multiple assignment operators for SpinLockMutex #9063

Job	Run time
Bazel noexcept	11m 44s
Bazel asan config	15m 0s
Bazel nortti	12m 25s
Bazel on MacOS	34m 32s
Bazel	12m 26s
Bazel with async export	12m 13s
Bazel valgrind	14m 24s
Bazel tsan config	13m 9s
Bazel with external abseil	12m 14s
Benchmark	8m 11s
CMake test (with abseil)	4m 33s
CMake clang 14 (maintainer mode, abiv2)	13m 40s
CMake clang 14 (maintainer mode, async)	14m 2s
CMake clang 14 (maintainer mode, sync)	13m 48s
CMake do not install test (with otlp-exporter)	13m 40s
CMake gcc 12 (maintainer mode, async)	7m 40s
CMake gcc 12 (maintainer mode, sync)	8m 7s
CMake install test (with abseil)	4m 23s
CMake test (with modern protobuf,grpc and abseil)	18m 55s
CMake msvc (maintainer mode)	7m 22s
CMake msvc (maintainer mode) with C++20	8m 3s
CMake test (with opentracing-shim)	4m 15s
CMake test (build shared libraries with otlp-exporter and static gRPC)	14m 7s
CMake test (with otlp-exporter)	14m 39s
CMake test (without otlp-exporter)	4m 32s
CMake C++14 test(GCC)	4m 4s
CMake C++17 test(GCC)	4m 41s
CMake C++20 test(Clang with libc++)	9m 17s
CMake C++20 test(GCC)	8m 29s
CMake test (without otlp-exporter and with async export)	5m 2s
Code coverage	11m 45s
Copyright	5s
DocFX check	1m 1s
Format	14s
markdown-lint	6s
misspell	7s
Plugin -> CMake	53s
CMake -> exporter proto	12m 35s
Bazel Windows	19m 56s
Plugin -> CMake Windows	6m 32s
CMake (With async export) -> exporter proto	12m 24s
CMake -> exporter proto (Build as DLL)	19m 48s
	6h 55m 3s

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