Change OTLP HTTP content_type default to binary #9247

Job	Run time
CMake clang 15 (maintainer mode, abiv2)	14m 29s
CMake clang 15 (maintainer mode, async)	14m 23s
CMake clang 15 (maintainer mode, sync)	13m 56s
CMake gcc 13 (maintainer mode, async)	7m 9s
CMake gcc 13 (maintainer mode, sync)	6m 37s
CMake msvc (maintainer mode)	8m 16s
CMake msvc (maintainer mode) with C++20	9m 55s
CMake test (without otlp-exporter)	5m 50s
CMake test (with abseil)	4m 57s
CMake test (with modern protobuf,grpc and abseil)	18m 31s
CMake test (with opentracing-shim)	4m 12s
CMake test (with otlp-exporter)	13m 36s
CMake C++14 test(GCC)	4m 4s
CMake C++17 test(GCC)	4m 32s
CMake C++20 test(Clang with libc++)	9m 47s
CMake C++20 test(GCC)	8m 19s
CMake C++23 test(Clang with libc++)	10m 43s
CMake C++23 test(GCC)	8m 36s
CMake test (without otlp-exporter and with async export)	4m 59s
Bazel asan config	14m 26s
Bazel noexcept	11m 40s
Bazel nortti	12m 34s
Bazel on MacOS	28m 47s
Bazel	12m 9s
Bazel with async export	12m 20s
Bazel tsan config	13m 5s
Bazel valgrind	14m 4s
Bazel with external abseil	12m 13s
Benchmark	8m 4s
CMake do not install test (with otlp-exporter)	14m 17s
CMake install test (with abseil)	4m 36s
CMake test (build shared libraries with otlp-exporter and static gRPC)	13m 23s
Plugin -> CMake	1m 8s
Code coverage	11m 50s
Copyright	6s
DocFX check	40s
Format	16s
markdown-lint	6s
misspell	9s
CMake -> exporter proto	12m 29s
Bazel Windows	20m 30s
Plugin -> CMake Windows	6m 36s
CMake (With async export) -> exporter proto	12m 54s
CMake -> exporter proto (Build as DLL)	27m 23s
	7h 18m 36s

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