simplify staged sync world (#2336)

cmd/integration/commands/snapshot_check.go

cmd/integration/commands/stages.go

cmd/integration/commands/state_stages.go

cmd/rpcdaemon/commands/send_transaction_test.go

cmd/rpcdaemon/commands/txpool_api_test.go

eth/backend.go

eth/ethconfig/config.go

eth/stagedsync/default_stages.go

eth/stagedsync/stage_execute.go

eth/stagedsync/stage_execute_test.go

eth/stagedsync/stagebuilder.go

eth/stagedsync/stagedsync.go

turbo/shards/state_change_accumulator.go

turbo/stages/mock_sentry.go

turbo/stages/sentry_mock_test.go

turbo/stages/stageloop.go