Add global label length limits #9

Job	Run time
Compliance testing	7m 43s
Go tests with previous Go version	12m 4s
Build Prometheus for common architectures (0)	11m 46s
Mixins tests	3m 25s
More Go tests	8m 5s
Build Prometheus for common architectures (2)	11m 46s
UI tests	2m 20s
Check generated parser	1m 11s
golangci-lint	3m 25s
Go tests	23m 7s
Go tests on Windows	8m 0s
codeql / Analyze (javascript)	1m 19s
fuzzing / Run Go Fuzz Tests (FuzzParseMetricSelector)	6m 41s
fuzzing / Run Go Fuzz Tests (FuzzParseOpenMetric)	6m 41s
Build Prometheus for common architectures (1)	11m 26s
fuzzing / Run Go Fuzz Tests (FuzzParseMetricText)	6m 36s
Build Prometheus for all architectures	-1s
fuzzing / Run Go Fuzz Tests (FuzzParseExpr)	6m 36s
Report status of build Prometheus for all architectures	-1s
fuzzing / Fuzzing	2s
Publish UI on npm Registry	1m 47s
Publish release artefacts	-1s
Publish main branch artifacts	-1s
	2h 13m 56s

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