Rename StartTime and Time fields of Aggregate processor

[kkondaka]

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Rename StartTime and Time fields of Aggregate processor to "AggregationStartTime" and "AggregationEndTime"

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Rename StartTime and Time fields of Aggregate processor to "AggregationStartTime" and "AggregationEndTime"

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[kkondaka]

These names are inconsistent in RAW mode. In OTEL mode, the names are part of JacksonMetric. I think the names in the OTEL mode are good. We should deprecate RAW mode.