Drop state_size_bytes from NexusOperationInfo

Remove state_size_bytes field and renumber execution_duration.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: stephanos

temporal/api/nexus/v1/message.proto

@@ -357,9 +357,7 @@ message NexusOperationExecutionListInfo {
 
     // Updated on terminal status.
     int64 state_transition_count = 10;
-    // Updated once on scheduled and once on terminal status.
-    int64 state_size_bytes = 11;
     // The difference between close time and scheduled time.
     // This field is only populated if the operation is closed.
-    google.protobuf.Duration execution_duration = 12;
+    google.protobuf.Duration execution_duration = 11;
 }