Remove unused field from xorAppender
Remove unused field from xorAppender

This field is not used, remove it.

Gouthamve/tsdb,kangwoo/prometheus,keegancsmith/prometheus,GoogleCloudPlatform/prometheus,kangwoo/prometheus,keegancsmith/prometheus,alileza/prometheus,prometheus/prometheus,prometheus/prometheus,kangwoo/prometheus,GoogleCloudPlatform/prometheus,alileza/prometheus,prometheus/prometheus,alileza/prometheus,alileza/prometheus,prometheus/prometheus,Gouthamve/prometheus,alileza/prometheus,keegancsmith/prometheus,GoogleCloudPlatform/prometheus,kangwoo/prometheus,Gouthamve/prometheus,keegancsmith/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,prometheus/tsdb,prometheus/prometheus,keegancsmith/prometheus,Gouthamve/prometheus,Gouthamve/prometheus