Add global label length limits #16

Job	Run time
UI tests	2m 10s
More Go tests	7m 54s
Go tests on Windows	10m 51s
Build Prometheus for common architectures (0)	11m 34s
Go tests	22m 59s
Build Prometheus for common architectures (2)	11m 47s
Build Prometheus for common architectures (1)	11m 22s
Check generated parser	1m 11s
Go tests with previous Go version	11m 42s
Mixins tests	3m 53s
Compliance testing	7m 52s
codeql / Analyze (javascript)	1m 17s
golangci-lint	3m 13s
fuzzing / Run Go Fuzz Tests (FuzzParseExpr)	6m 32s
fuzzing / Run Go Fuzz Tests (FuzzParseMetricSelector)	6m 43s
fuzzing / Run Go Fuzz Tests (FuzzParseMetricText)	6m 43s
fuzzing / Run Go Fuzz Tests (FuzzParseOpenMetric)	6m 34s
Build Prometheus for all architectures	0s
Report status of build Prometheus for all architectures	0s
Publish UI on npm Registry	1m 49s
fuzzing / Fuzzing	2s
Publish release artefacts	0s
Publish main branch artifacts	-1s
	2h 16m 7s

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