docs: the CloudVmClusterProperties.system_version field is no longer labeled as output only

PiperOrigin-RevId: 711457154

Author: Google APIs

google/cloud/oracledatabase/v1/vm_cluster.proto

@@ -216,8 +216,8 @@ message CloudVmClusterProperties {
   // Required. Number of enabled CPU cores.
   int32 cpu_core_count = 26 [(google.api.field_behavior) = REQUIRED];
 
-  // Output only. Operating system version of the image.
-  string system_version = 27 [(google.api.field_behavior) = OUTPUT_ONLY];
+  // Optional. Operating system version of the image.
+  string system_version = 27 [(google.api.field_behavior) = OPTIONAL];
 
   // Output only. OCIDs of scan IPs.
   repeated string scan_ip_ids = 28 [(google.api.field_behavior) = OUTPUT_ONLY];