Remove the onResume.fromData field from ActorTemplate #2027

Remove the onResume setting from ActorTemplate. Actor lifecycle v2 will not support restoring by combining the golden snapshot's own files with an actor's data snapshot.

• ateapi: drop the golden-snapshot resolution on resume and the DATA_ON_GOLDEN path in workflow_resume.go.
• atelet: remove SNAPSHOT_SCOPE_DATA_ON_GOLDEN, RestoreRequest.base_config / golden_snapshot_files, and the combined golden + data download.
• Docs: remove references to golden + data merge on resume.