SSE: Support time series frames with non-nullable float64 values (#32608)

* SSE: fix reduce to handle non-null
* add type for data.Field that is float64 or *float64
* resample fix for non-null input case, add couple non-null tests

pkg/expr/classic/classic.go

@@ -86,6 +86,7 @@ func (ccc *ConditionsCmd) Execute(ctx context.Context, vars mathexp.Vars) (mathe
 			}
 
 			reducedNum := c.Reducer.Reduce(series)
+
 			// TODO handle error / no data signals
 			thisCondNoDataFound := reducedNum.GetFloat64Value() == nil