add primary storage metrics for ImageStoreBackupStorage
add primary storage metrics for ImageStoreBackupStorage

Alvin-Lau/zstack,Alvin-Lau/zstack,zsyzsyhao/zstack,camilesing/zstack,liningone/zstack,camilesing/zstack,zstackorg/zstack,AlanJager/zstack,MaJin1996/zstack,WangXijue/zstack,HeathHose/zstack,zstackio/zstack,hhjuliet/zstack,MatheMatrix/zstack,MaJin1996/zstack,HeathHose/zstack,zxwing/zstack-1,zstackorg/zstack,mingjian2049/zstack,zstackio/zstack,MatheMatrix/zstack,zxwing/zstack-1,winger007/zstack,AlanJinTS/zstack,AlanJinTS/zstack,winger007/zstack,Alvin-Lau/zstack,zsyzsyhao/zstack,AlanJinTS/zstack,WangXijue/zstack,zxwing/zstack-1,AlanJager/zstack,liningone/zstack,WangXijue/zstack,liningone/zstack,HeathHose/zstack,zstackio/zstack,mingjian2049/zstack,mingjian2049/zstack,AlanJager/zstack,MatheMatrix/zstack,camilesing/zstack,hhjuliet/zstack