Avoid synchronization bug involving DDC memory backend and value-locking that can occur during disable of the memory backend.

#rb danny.couture
#preflight 61f461496b5aea38e5c43f49

#ROBOMERGE-AUTHOR: zousar.shaker
#ROBOMERGE-SOURCE: CL 18779214 in //UE5/Release-5.0/... via CL 18780677 via CL 18781162
#ROBOMERGE-BOT: UE5 (Release-Engine-Test -> Main) (v903-18687472)

[CL 18781198 by zousar shaker in ue5-main branch]

Engine/Source/Developer/DerivedDataCache/Private/MemoryDerivedDataBackend.cpp

@@ -127,6 +127,12 @@ private:
 			, Size(InSize)
 		{
 		}
+
+		~FCacheValue()
+		{
+			// Ensure we don't begin destruction of this value while our own PutCachedData function is holding this lock
+			FWriteScopeLock WriteLock(DataLock);
+		}
 	};
 
 	FORCEINLINE int32 CalcSerializedCacheValueSize(const FString& Key, const FCacheValue& Val)