fix: use right operation type in server streaming callable

Author: diegomarquezp

gax-java/gax/src/main/java/com/google/api/gax/tracing/TracedServerStreamingCallable.java

@@ -71,7 +71,7 @@ public TracedServerStreamingCallable(
     this.tracerFactory = Preconditions.checkNotNull(tracerFactory, "tracerFactory can't be null");
     this.apiTracerContext =
         Preconditions.checkNotNull(apiTracerContext, "apiTracerContext can't be null").toBuilder()
-            .setOperationType(OperationType.ClientStreaming)
+            .setOperationType(OperationType.ServerStreaming)
             .build();
     this.innerCallable = Preconditions.checkNotNull(innerCallable, "innerCallable can't be null");
     this.spanName = SpanName.of(this.apiTracerContext);