[exporters/prometheus] Sanitize labels according to Prometheus spec (… #8559

Job	Run time
CMake test (without otlp-exporter)	7m 15s
CMake clang 14 (maintainer mode, sync)	23m 47s
CMake gcc 12 (maintainer mode, async)	15m 31s
CMake gcc 12 (maintainer mode, C++11, async)	13m 38s
CMake gcc 12 (maintainer mode, sync)	11m 54s
CMake test (with abseil)	6m 40s
CMake clang 14 (maintainer mode, async)	20m 4s
CMake msvc (maintainer mode)	10m 32s
CMake gcc 4.8 (without otlp exporter)	7m 51s
CMake test (with opentracing-shim)	7m 39s
CMake test (without otlp-exporter and with async export)	8m 34s
CMake gcc 4.8 (with otlp exporter)	13m 55s
CMake do not install test (with otlp-exporter)	25m 9s
CMake test (build shared libraries with otlp-exporter and static gRPC)	21m 5s
CMake test (with modern protobuf,grpc and abseil)	41m 14s
CMake test (with otlp-exporter)	25m 7s
CMake C++20 test(Clang with libc++)	11m 21s
CMake C++20 test(GCC)	12m 24s
Bazel asan config	10m 17s
Bazel noexcept	20m 8s
Bazel nortti	18m 29s
Bazel	19m 2s
Bazel with async export	31m 0s
Bazel tsan config	19m 49s
Bazel valgrind	23m 32s
CMake install test (with abseil)	9m 0s
Bazel with external abseil	22m 37s
Plugin -> CMake	1m 15s
Bazel on MacOS	30m 36s
Benchmark	14m 27s
Code coverage	13m 31s
Copyright	9s
Format	19s
markdown-lint	14s
misspell	12s
CMake -> exporter proto	23m 28s
Bazel Windows	42m 44s
Plugin -> CMake Windows	9m 54s
CMake (With async export) -> exporter proto	17m 38s
CMake -> exporter proto (Build as DLL)	24m 16s
DocFX check	1m 13s
	10h 37m 30s

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