Remove unnecessary spaces ahead of custom yaml.

cluster/gce/gci/configure-helper.sh

@@ -2238,7 +2238,7 @@ function setup-addon-custom-yaml {
   if [ -n "${custom_yaml:-}" ]; then
     # Replace with custom manifest.
     cat > "${manifest_path}" <<EOF
-    $custom_yaml
+$custom_yaml
 EOF
   fi
 }
@@ -2639,4 +2639,4 @@ if [[ "$#" -eq 1 && "${1}" == "--source-only" ]]; then
    :
 else
    main "${@}"
-fi
\ No newline at end of file
+fi