ACP-77: Implement `SetSubnetValidatorWeightTx` #8768

Job	Run time
Unit (macos-12)	11m 15s
Fuzz	14m 20s
Unit (ubuntu-20.04)	4m 44s
Up-to-date protobuf	26s
Unit (ubuntu-22.04)	7m 30s
Unit (ubuntu-24.04)	4m 38s
Protobuf Lint	6s
Unit (windows-2022)	9m 54s
e2e_existing_network	4m 20s
e2e_post_etna	12m 46s
Unit (custom-arm64-jammy)	14m 8s
Unit (custom-arm64-noble)	14m 33s
e2e_pre_etna	11m 6s
Lint	3m 46s
Upgrade	3m 17s
Up-to-date mocks	1m 58s
Run bootstrap monitor e2e tests	6m 43s
Up-to-date go.mod and go.sum	14s
Build Antithesis xsvm images	11m 46s
Build Antithesis avalanchego images	8m 14s
Image build	10m 45s
	2h 36m 29s

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