private OperationQuotaCharger prepareQuotaCharger() {
      operationQuotaCharger.setBlobId(chunkBlobId);
      operationQuotaCharger.setChunkSize(chunkSize);
      return operationQuotaCharger;
    }
Set the blobId and chunkSize in the operationQuotaCharger, and return the {@link OperationQuotaCharger} object.
Note that this method might set the blobId and chunkSize for the same chunk multiple times. This is ok because
these are idempotent operation for the same chunk.
@return OperationQuotaCharger object.
ambry-router/src/main/java/com/github/ambry/router/GetBlobOperation.java