Use gRPC ClientConn for otlpmetricgrpc client connection handling

CHANGELOG.md

@@ -12,6 +12,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - The `"go.opentelemetry.io/otel/exporter/otel/otlptrace/otlptracegrpc".Client` now uses the underlying gRPC `ClientConn` to handle name resolution, TCP connection establishment (with retries and backoff) and TLS handshakes, and handling errors on established connections by re-resolving the name and reconnecting. (#2329)
 - Changed the project minimum supported Go version from 1.15 to 1.16. (#2412)
+- The `"go.opentelemetry.io/otel/exporter/otel/otlpmetric/otlpmetricgrpc".Client` now uses the underlying gRPC `ClientConn` to handle name resolution, TCP connection establishment (with retries and backoff) and TLS handshakes, and handling errors on established connections by re-resolving the name and reconnecting. (#2425)
 
 ### Removed
 

exporters/otlp/otlpmetric/go.mod

@@ -12,7 +12,6 @@ require (
 	go.opentelemetry.io/otel/sdk/export/metric v0.25.0
 	go.opentelemetry.io/otel/sdk/metric v0.25.0
 	go.opentelemetry.io/proto/otlp v0.11.0
-	google.golang.org/genproto v0.0.0-20200526211855-cb27e3aa2013
 	google.golang.org/grpc v1.42.0
 	google.golang.org/protobuf v1.27.1
 )