Improve roundtrip behavior of rpc methods.

Methods without options have three ways of ending their definition: {}, ;, and {};.  This tracks this choice in metadata and restores it when writing.

PiperOrigin-RevId: 582903253
diff --git a/src/google/protobuf/editions/golden/editions_transform_proto2.proto b/src/google/protobuf/editions/golden/editions_transform_proto2.proto
index 88940ba..207ebea 100644
--- a/src/google/protobuf/editions/golden/editions_transform_proto2.proto
+++ b/src/google/protobuf/editions/golden/editions_transform_proto2.proto
@@ -34,7 +34,7 @@
 }
 
 service BasicService {
-  rpc BasicMethod(EmptyMessage) returns (EmptyMessage);
+  rpc BasicMethod(EmptyMessage) returns (EmptyMessage) {}
 }
 
 // clang-format off