[Metrics] Make context optional for histogram instruments in Metrics SDK #8793

Job	Run time
Bazel noexcept	12m 53s
Bazel asan config	11m 58s
Bazel nortti	12m 47s
Bazel on MacOS	21m 1s
Bazel	12m 33s
Bazel with async export	16m 43s
Bazel tsan config	13m 35s
Bazel valgrind	14m 40s
Bazel with external abseil	14m 39s
Benchmark	8m 11s
CMake test (with abseil)	4m 44s
CMake clang 14 (maintainer mode, abiv2)	14m 0s
CMake clang 14 (maintainer mode, async)	13m 53s
CMake clang 14 (maintainer mode, sync)	13m 27s
CMake do not install test (with otlp-exporter)	23m 2s
CMake gcc 12 (maintainer mode, async)	8m 7s
CMake gcc 12 (maintainer mode, sync)	8m 4s
CMake install test (with abseil)	4m 15s
CMake test (with modern protobuf,grpc and abseil)	18m 15s
CMake msvc (maintainer mode)	9m 29s
CMake test (with opentracing-shim)	3m 58s
CMake test (build shared libraries with otlp-exporter and static gRPC)	14m 20s
CMake test (with otlp-exporter)	14m 47s
CMake test (without otlp-exporter)	4m 36s
CMake C++14 test(GCC)	4m 22s
CMake C++17 test(GCC)	4m 39s
CMake C++20 test(Clang with libc++)	9m 11s
CMake C++20 test(GCC)	10m 52s
CMake test (without otlp-exporter and with async export)	4m 27s
Code coverage	13m 57s
Copyright	5s
DocFX check	35s
Format	21s
markdown-lint	6s
misspell	5s
Plugin -> CMake	1m 11s
CMake -> exporter proto	12m 1s
Bazel Windows	19m 36s
Plugin -> CMake Windows	6m 31s
CMake (With async export) -> exporter proto	11m 40s
CMake -> exporter proto (Build as DLL)	12m 9s
	6h 45m 45s

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