fix(write): Successful writes increment write error statistics incorrectly.

In v1.8.3 and earlier, the write path through (*PointsWriter) writeToShardWithContext() always increments the WriteErr count in the debug variables, and does not increment the WriteOK count.
https://github.com/influxdata/influxdb/blob/v1.8.3/coordinator/points_writer.go line 450 should be an else if err != nil { instead of an else
This has been reported in a customer cloud instance, and verified under a debugger.

https://github.com/influxdata/influxdb/issues/20098

coordinator/points_writer.go

@@ -447,11 +447,10 @@ func (w *PointsWriter) writeToShardWithContext(ctx context.Context, shard *meta.
 			atomic.AddInt64(&w.stats.WriteErr, 1)
 			return err
 		}
-	} else {
+	} else if err != nil {
 		atomic.AddInt64(&w.stats.WriteErr, 1)
 		return err
 	}
-
 	atomic.AddInt64(&w.stats.WriteOK, 1)
 	return nil
 }