ACP-77: Implement `SetSubnetValidatorWeightTx` #8800

Job	Run time
e2e_existing_network	4m 11s
e2e_post_etna	13m 3s
e2e_pre_etna	11m 7s
Fuzz	14m 12s
Unit (macos-12)	6m 34s
Unit (ubuntu-20.04)	4m 42s
Unit (ubuntu-22.04)	7m 35s
Upgrade	3m 13s
Unit (ubuntu-24.04)	4m 39s
Protobuf Lint	7s
Unit (windows-2022)	11m 14s
Unit (custom-arm64-jammy)	14m 1s
Lint	3m 48s
Unit (custom-arm64-noble)	14m 45s
Up-to-date protobuf	27s
Up-to-date mocks	2m 1s
Run bootstrap monitor e2e tests	6m 38s
Up-to-date go.mod and go.sum	22s
Build Antithesis avalanchego images	8m 19s
Image build	10m 20s
Build Antithesis xsvm images	11m 42s
	2h 33m 0s

Provide feedback