Config sync: Only copy paths to prod which are actually there

Stored files may be removed by external sources.

lib/remote/apilistener-filesync.cpp

@@ -547,6 +547,9 @@ void ApiListener::TryActivateZonesStageCallback(const ProcessResult& pr,
 
 		// Copy all synced configuration files from stage to production.
 		for (const String& path : relativePaths) {
+			if (!Utility::PathExists(path))
+				continue;
+
 			Log(LogInformation, "ApiListener")
 				<< "Copying file '" << path << "' from config sync staging to production zones directory.";