Fix stemcell os

Author: mariash

ci/tasks/test-bdrats.sh

@@ -43,7 +43,7 @@ source /tmp/local-bosh/director/env
 BOSH_SSH_KEY="$(bosh int /tmp/local-bosh/director/creds.yml --path /jumpbox_ssh/private_key --json | jq .Blocks[0])"
 BOSH_HOST="${BOSH_ENVIRONMENT}"
 
-stemcell_os="$(cut -d- -f8-9 < stemcell/url )"
+stemcell_os="$(cut -d- -f8-9 < stemcell/url | sed 's/\.tgz//')"
 bosh_ca_cert_json_value="$(awk '{printf "%s\\n", $0}' "${BOSH_CA_CERT}")"
 
 cat > integration-config.json <<EOF