Remove duplicate install command in CMakeLists.txt for api #8977

Job	Run time
Bazel asan config	15m 22s
Bazel nortti	12m 13s
Bazel noexcept	12m 1s
Bazel on MacOS	19m 55s
Bazel	12m 8s
Bazel with async export	12m 12s
Bazel tsan config	13m 26s
Bazel valgrind	14m 30s
Bazel with external abseil	12m 38s
Benchmark	8m 9s
CMake test (with abseil)	5m 50s
CMake clang 14 (maintainer mode, abiv2)	13m 48s
CMake clang 14 (maintainer mode, async)	14m 46s
CMake clang 14 (maintainer mode, sync)	13m 47s
CMake do not install test (with otlp-exporter)	14m 18s
CMake gcc 12 (maintainer mode, async)	7m 50s
CMake gcc 12 (maintainer mode, sync)	7m 52s
CMake install test (with abseil)	4m 19s
CMake test (with modern protobuf,grpc and abseil)	19m 36s
CMake msvc (maintainer mode)	7m 17s
CMake msvc (maintainer mode) with C++20	8m 33s
CMake test (with opentracing-shim)	4m 23s
CMake test (build shared libraries with otlp-exporter and static gRPC)	14m 50s
CMake test (with otlp-exporter)	15m 7s
CMake test (without otlp-exporter)	4m 44s
CMake C++14 test(GCC)	4m 13s
CMake C++17 test(GCC)	4m 43s
CMake C++20 test(Clang with libc++)	9m 31s
CMake C++20 test(GCC)	8m 11s
CMake test (without otlp-exporter and with async export)	4m 49s
Code coverage	11m 36s
Copyright	7s
DocFX check	1m 1s
Format	12s
markdown-lint	8s
misspell	8s
Plugin -> CMake	1m 7s
CMake -> exporter proto	12m 16s
Bazel Windows	23m 6s
Plugin -> CMake Windows	6m 41s
CMake (With async export) -> exporter proto	11m 53s
CMake -> exporter proto (Build as DLL)	12m 6s
	6h 41m 22s

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