Simplify common.Engine API #8273

Job	Run time
Fuzz	14m 18s
e2e_pre_etna	11m 8s
Up-to-date mocks	1m 57s
Protobuf Lint	6s
Up-to-date protobuf	23s
e2e_existing_network	4m 4s
e2e_post_etna	11m 34s
Lint	3m 15s
Unit (macos-12)	8m 47s
Upgrade	3m 7s
Unit (ubuntu-20.04)	4m 9s
Up-to-date go.mod and go.sum	16s
Unit (ubuntu-22.04)	6m 47s
Build Antithesis avalanchego images	8m 17s
Unit (ubuntu-24.04)	4m 15s
Build Antithesis xsvm images	11m 48s
Unit (windows-2022)	9m 29s
Image build	10m 29s
Unit (custom-arm64-jammy)	12m 41s
Unit (custom-arm64-noble)	14m 1s
	2h 20m 51s

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