ci/prow-rhcos.sh: use `--transient`
So we test it, and so we also gain the speed benefits.
@@ -17,5 +17,5 @@ esac
export COSA_SKIP_OVERLAY=1
# Create a temporary cosa workdir
cd "$(mktemp -d)"
-cosa init -b "${RHCOS_BRANCH}" https://github.com/openshift/os
+cosa init --transient -b "${RHCOS_BRANCH}" https://github.com/openshift/os
exec src/config/ci/prow-build-test-qemu.sh
