Correctly synchronize RecoveryState#Translog internal state (#81528)

* Correctly synchronize RecoveryState#Translog internal state

We must synchronize all access to the internal state, otherwise
there's no read/write memory barriers when deserializing/serialize
the state from the wire.

* Remove synchronization from the constructor

Co-authored-by: Elastic Machine <[email protected]>

Author: arteam

server/src/main/java/org/elasticsearch/indices/recovery/RecoveryState.java

@@ -486,10 +486,12 @@ public Translog(StreamInput in) throws IOException {
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             super.writeTo(out);
-            out.writeVInt(recovered);
-            out.writeVInt(total);
-            out.writeVInt(totalOnStart);
-            out.writeVInt(totalLocal);
+            synchronized (this) {
+                out.writeVInt(recovered);
+                out.writeVInt(total);
+                out.writeVInt(totalOnStart);
+                out.writeVInt(totalLocal);
+            }
         }
 
         public synchronized void reset() {