Adjust #ifdef EXEC_BACKEND RemovePgTempFilesInDir() call.

Other callers were adjusted in the course of
dc6c4c9d.

Per buildfarm.

src/backend/storage/file/fd.c

@@ -3020,7 +3020,7 @@ RemovePgTempFiles(void)
 	 * DataDir as well.
 	 */
 #ifdef EXEC_BACKEND
-	RemovePgTempFilesInDir(PG_TEMP_FILES_DIR);
+	RemovePgTempFilesInDir(PG_TEMP_FILES_DIR, false);
 #endif
 }