The previous ensure_fields helper used python3 which is not available in
alpine:3.19, causing exit 127 in the cloud init container.
Replaced with ensure_field (per-field, no python/jq) that uses only
busybox sh, wget, sed, and awk. Also fixed the HTTP status grep pattern
in create_collection and ensure_field to match only the response header
line (^ HTTP/) instead of the wget error line, eliminating the spurious
'unexpected status server' warnings.
fe204598a2