Add Etna P-chain metrics #8847

Job	Run time
e2e_pre_etna	11m 1s
Protobuf Lint	6s
Up-to-date mocks	2m 0s
Up-to-date protobuf	22s
e2e_post_etna	13m 34s
Fuzz	14m 12s
Up-to-date go.mod and go.sum	10s
Lint	3m 46s
Build Antithesis avalanchego images	8m 27s
Build Antithesis xsvm images	11m 44s
Image build	10m 37s
Unit (macos-12)	6m 33s
Upgrade	3m 12s
Unit (ubuntu-20.04)	4m 41s
Run bootstrap monitor e2e tests	6m 45s
Unit (ubuntu-22.04)	7m 14s
e2e_existing_network	4m 12s
Unit (ubuntu-24.04)	4m 42s
Unit (windows-2022)	9m 52s
Unit (custom-arm64-jammy)	13m 37s
Unit (custom-arm64-noble)	14m 8s
	2h 30m 55s

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