Remove temporality from the Summary

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

Author: bogdandrutu

opentelemetry/proto/metrics/v1/metrics.proto

@@ -216,10 +216,6 @@ message MetricDescriptor {
     //
     // Determines the value type of the exemplars.
     MeasurementValueType measurement_value_type = 1;
-
-    // aggregation_temporality describes if the aggregator reports delta changes
-    // since last report time, or cumulative changes since a fixed start time.
-    AggregationTemporality aggregation_temporality = 2;
   }
 
   // Type determines the aggregation type (if any) of the metric, what is the