[BUG] Transforming Metric Value to Aggregated Value Type during Star Tree Merges

[sarthakaggarwal97]

Describe the bug

Whenever we were reading the star tree documents from the segment during merges, we were transforming the segment metric doc value to its original field type. Instead, it should be converted to aggregator value type since before indexing doc values, the metric type is of the aggregator value type.

For Example.

If there is a Half Float Metric Field, with the SUM metric (double type). The Half Float Metric field is converted to double during aggregation and indexed as "double". During reads, the metric should be converted from sortable long back to double only for accurate aggregations.

Related component

Indexing:Performance

To Reproduce

Merges during star tree will break for any other data type than double

Expected behavior

The metric should be converted to aggregated value type during merges.

Additional Details

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