[server] Enhance server storage logs (#9886)

Currently, applications print lots of "Retrieved value from
server storage" messages on startup, even if the value was
actually not found in the storage. Make sure the logs are
printed only when a value is really loaded, stored or
deleted.

src/app/server/Server.h

@@ -86,20 +86,23 @@ class Server : public Messaging::ExchangeDelegate
     {
         CHIP_ERROR SyncGetKeyValue(const char * key, void * buffer, uint16_t & size) override
         {
-            ChipLogProgress(AppServer, "Retrieved value from server storage.");
-            return DeviceLayer::PersistedStorage::KeyValueStoreMgr().Get(key, buffer, size);
+            ReturnErrorOnFailure(DeviceLayer::PersistedStorage::KeyValueStoreMgr().Get(key, buffer, size));
+            ChipLogProgress(AppServer, "Retrieved from server storage: %s", key);
+            return CHIP_NO_ERROR;
         }
 
         CHIP_ERROR SyncSetKeyValue(const char * key, const void * value, uint16_t size) override
         {
-            ChipLogProgress(AppServer, "Stored value in server storage");
-            return DeviceLayer::PersistedStorage::KeyValueStoreMgr().Put(key, value, size);
+            ReturnErrorOnFailure(DeviceLayer::PersistedStorage::KeyValueStoreMgr().Put(key, value, size));
+            ChipLogProgress(AppServer, "Saved into server storage: %s", key);
+            return CHIP_NO_ERROR;
         }
 
         CHIP_ERROR SyncDeleteKeyValue(const char * key) override
         {
-            ChipLogProgress(AppServer, "Delete value in server storage");
-            return DeviceLayer::PersistedStorage::KeyValueStoreMgr().Delete(key);
+            ReturnErrorOnFailure(DeviceLayer::PersistedStorage::KeyValueStoreMgr().Delete(key));
+            ChipLogProgress(AppServer, "Deleted from server storage: %s", key);
+            return CHIP_NO_ERROR;
         }
     };