Remove unused aggregator ca key

Author: wenjiaswe

cluster/gce/gci/configure-helper.sh

@@ -546,9 +546,6 @@ function create-master-pki {
   write-pki-data "${SERVICEACCOUNT_KEY}" "${SERVICEACCOUNT_KEY_PATH}"
 
   if [[ ! -z "${REQUESTHEADER_CA_CERT:-}" ]]; then
-    AGGREGATOR_CA_KEY_PATH="${pki_dir}/aggr_ca.key"
-    write-pki-data "${AGGREGATOR_CA_KEY}" "${AGGREGATOR_CA_KEY_PATH}"
-
     REQUESTHEADER_CA_CERT_PATH="${pki_dir}/aggr_ca.crt"
     write-pki-data "${REQUESTHEADER_CA_CERT}" "${REQUESTHEADER_CA_CERT_PATH}"