Update http metric exporter batch return to be like grpc

Author: tammy-baylis-swi

exporter/opentelemetry-exporter-otlp-proto-http/src/opentelemetry/exporter/otlp/proto/http/metric_exporter/__init__.py

@@ -296,10 +296,10 @@ def export(
             )
 
             if batch_result == MetricExportResult.FAILURE:
-                export_result = MetricExportResult.FAILURE
-                # Don't retry; move on to next batch
+                # If any batch fails, return failure immediately
+                return MetricExportResult.FAILURE
 
-        # Return last result after all batches are attempted
+        # Return SUCCESS only if all batches succeeded
         return export_result
 
     def _split_metrics_data(