fix(build): check latest env image to decide a rebuild

- we now have preflight images which break the previous logic of checking
the most recent image timestamp, check image tagged with latest

script/actions_utils/container_timestamp_check.sh

@@ -58,7 +58,8 @@ ENV_JSON=$(curl \
 -H "Authorization: token ${TOKEN}" \
 "${ENV_IMG_ENDPOINT_URL}")
 
-ENV_IMG_TIMESTAMP=$(echo "${ENV_JSON}" | jq -r 'sort_by(.updated_at)[-1].updated_at')
+ENV_IMG_TIMESTAMP=$(echo "${ENV_JSON}" | \
+jq -rc '.[] | select(.metadata.container.tags[] | contains("latest")).updated_at'
 
 echo "Base timestamp: ${BASE_IMG_TIMESTAMP}"
 echo "Env timestamp:  ${ENV_IMG_TIMESTAMP}"