[Metrics] Make context optional for histogram instruments in Metrics SDK #8790

Job	Run time
Bazel asan config	2m 33s
Bazel noexcept	9m 40s
Bazel nortti	5m 27s
Bazel on MacOS	9m 45s
Bazel	9m 48s
Bazel with async export	4m 26s
Bazel tsan config	9m 46s
Bazel valgrind	4m 45s
Bazel with external abseil	9m 3s
Benchmark	1m 34s
CMake test (with abseil)	2m 42s
CMake clang 14 (maintainer mode, abiv2)	9m 31s
CMake clang 14 (maintainer mode, async)	9m 47s
CMake clang 14 (maintainer mode, sync)	9m 37s
CMake do not install test (with otlp-exporter)	10m 48s
CMake gcc 12 (maintainer mode, async)	5m 13s
CMake gcc 12 (maintainer mode, sync)	6m 14s
CMake install test (with abseil)	2m 25s
CMake test (with modern protobuf,grpc and abseil)	14m 58s
CMake msvc (maintainer mode)	7m 1s
CMake test (with opentracing-shim)	2m 39s
CMake test (build shared libraries with otlp-exporter and static gRPC)	10m 36s
CMake test (with otlp-exporter)	10m 41s
CMake test (without otlp-exporter)	2m 17s
CMake C++14 test(GCC)	3m 12s
CMake C++17 test(GCC)	3m 26s
CMake C++20 test(Clang with libc++)	3m 40s
CMake C++20 test(GCC)	4m 5s
CMake test (without otlp-exporter and with async export)	2m 7s
Code coverage	2m 49s
Copyright	5s
DocFX check	52s
Format	20s
markdown-lint	13s
misspell	4s
Plugin -> CMake	1m 26s
CMake -> exporter proto	9m 18s
Bazel Windows	7m 11s
Plugin -> CMake Windows	5m 46s
CMake (With async export) -> exporter proto	11m 16s
CMake -> exporter proto (Build as DLL)	11m 22s
	3h 58m 28s

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