Add utf8 support to the prometheus exporter #14264

Job	Run time
test-bench	1m 18s
test-concurrent-safe	4m 5s
lint	2m 54s
compatibility-test (1.23.0, ubuntu-latest, 386)	1m 21s
compatibility-test (1.23.0, ubuntu-latest, amd64)	1m 17s
test-race	2m 14s
test-coverage	1m 20s
compatibility-test (1.23.0, macos-13, amd64)	2m 34s
compatibility-test (1.23.0, macos-latest, arm64)	1m 27s
compatibility-test (1.23.0, windows-latest, 386)	2m 45s
compatibility-test (1.23.0, windows-latest, amd64)	2m 41s
compatibility-test (1.23.0, actuated-arm64-2cpu-8gb, arm64)	2m 19s
compatibility-test (~1.22.5, ubuntu-latest, 386)	1m 10s
compatibility-test (~1.22.5, ubuntu-latest, amd64)	1m 12s
compatibility-test (~1.22.5, macos-13, amd64)	2m 3s
compatibility-test (~1.22.5, macos-latest, arm64)	1m 31s
compatibility-test (~1.22.5, windows-latest, 386)	2m 34s
compatibility-test (~1.22.5, windows-latest, amd64)	3m 45s
compatibility-test (~1.22.5, actuated-arm64-2cpu-8gb, arm64)	2m 25s
codecov	6s
test-compatibility	1s
	41m 2s

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